diff --git a/build.sbt b/build.sbt
index a266f804..07e2867a 100644
--- a/build.sbt
+++ b/build.sbt
@@ -60,7 +60,7 @@ ThisBuild / githubWorkflowEnv ++= List("PGP_PASSPHRASE", "PGP_SECRET", "SONATYPE
 val Versions = new {
   val catsCore = "2.8.0"
   val catsEffect = "3.3.14"
-  val catsEffect2 = "2.5.5"
+  val catsEffect2 = "3.5.2"
   val circe = "0.14.6"
   val jsoniter = "2.21.4"
   val monix = "3.4.1"
diff --git a/oauth2-cache-ce2/src/main/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CachingAccessTokenProvider.scala b/oauth2-cache-ce2/src/main/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CachingAccessTokenProvider.scala
index b72e7b19..1c9b2f62 100644
--- a/oauth2-cache-ce2/src/main/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CachingAccessTokenProvider.scala
+++ b/oauth2-cache-ce2/src/main/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CachingAccessTokenProvider.scala
@@ -4,7 +4,6 @@ import cats.Monad
 import cats.data.OptionT
 import cats.effect.Clock
 import cats.effect.Concurrent
-import cats.effect.concurrent.Semaphore
 import cats.syntax.all._
 import com.ocadotechnology.sttp.oauth2.cache.ExpiringCache
 import com.ocadotechnology.sttp.oauth2.cache.ce2.CachingAccessTokenProvider.TokenWithExpirationTime
@@ -15,6 +14,7 @@ import com.ocadotechnology.sttp.oauth2.Secret
 
 import java.time.Instant
 import scala.concurrent.duration.Duration
+import cats.effect.std.Semaphore
 
 final class CachingAccessTokenProvider[F[_]: Monad: Clock](
   delegate: AccessTokenProvider[F],
diff --git a/oauth2-cache-ce2/src/main/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CatsRefExpiringCache.scala b/oauth2-cache-ce2/src/main/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CatsRefExpiringCache.scala
index 2e744c14..ef79ecd0 100644
--- a/oauth2-cache-ce2/src/main/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CatsRefExpiringCache.scala
+++ b/oauth2-cache-ce2/src/main/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CatsRefExpiringCache.scala
@@ -2,7 +2,6 @@ package com.ocadotechnology.sttp.oauth2.cache.ce2
 
 import cats.Monad
 import cats.data.OptionT
-import cats.effect.concurrent.Ref
 import cats.effect.Clock
 import cats.effect.Sync
 import cats.implicits._
@@ -10,6 +9,7 @@ import com.ocadotechnology.sttp.oauth2.cache.ExpiringCache
 import com.ocadotechnology.sttp.oauth2.cache.ce2.CatsRefExpiringCache.Entry
 
 import java.time.Instant
+import cats.effect.Ref
 
 final class CatsRefExpiringCache[F[_]: Monad: Clock, K, V] private (ref: Ref[F, Map[K, Entry[V]]]) extends ExpiringCache[F, K, V] {
 
diff --git a/oauth2-cache-ce2/src/test/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CachingAccessTokenProviderParallelSpec.scala b/oauth2-cache-ce2/src/test/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CachingAccessTokenProviderParallelSpec.scala
index fb761000..2adf4fbb 100644
--- a/oauth2-cache-ce2/src/test/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CachingAccessTokenProviderParallelSpec.scala
+++ b/oauth2-cache-ce2/src/test/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CachingAccessTokenProviderParallelSpec.scala
@@ -1,10 +1,7 @@
 package com.ocadotechnology.sttp.oauth2.cache.ce2
 
 import cats.FlatMap
-import cats.effect.ContextShift
 import cats.effect.IO
-import cats.effect.Timer
-import cats.effect.concurrent.Ref
 import cats.syntax.all._
 import com.ocadotechnology.sttp.oauth2.ClientCredentialsToken.AccessTokenResponse
 import com.ocadotechnology.sttp.oauth2.cache.ExpiringCache
@@ -19,11 +16,12 @@ import org.scalatest.wordspec.AnyWordSpec
 import java.time.Instant
 import scala.concurrent.ExecutionContext
 import scala.concurrent.duration._
+import cats.effect.{ Ref, Temporal }
 
 class CachingAccessTokenProviderParallelSpec extends AnyWordSpec with Matchers {
   private val ec: ExecutionContext = ExecutionContext.global
   implicit lazy val cs: ContextShift[IO] = IO.contextShift(ec)
-  implicit val clock: Timer[IO] = IO.timer(ec)
+  implicit val clock: Temporal[IO] = IO.timer(ec)
 
   private val testScope: Option[Scope] = Scope.of("test-scope")
   private val token = AccessTokenResponse(Secret("secret"), None, 10.seconds, testScope)
@@ -64,7 +62,7 @@ class CachingAccessTokenProviderParallelSpec extends AnyWordSpec with Matchers {
     override def get(key: K): F[Option[V]] = delegate.get(key)
 
     override def put(key: K, value: V, expirationTime: Instant): F[Unit] =
-      Timer[F].sleep(sleepDuration) *> delegate.put(key, value, expirationTime)
+      Temporal[F].sleep(sleepDuration) *> delegate.put(key, value, expirationTime)
 
     override def remove(key: K): F[Unit] = delegate.remove(key)
   }
diff --git a/oauth2-cache-ce2/src/test/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CachingAccessTokenProviderSpec.scala b/oauth2-cache-ce2/src/test/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CachingAccessTokenProviderSpec.scala
index 437020b1..fa6368d4 100644
--- a/oauth2-cache-ce2/src/test/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CachingAccessTokenProviderSpec.scala
+++ b/oauth2-cache-ce2/src/test/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CachingAccessTokenProviderSpec.scala
@@ -1,9 +1,6 @@
 package com.ocadotechnology.sttp.oauth2.cache.ce2
 
-import cats.effect.ContextShift
 import cats.effect.IO
-import cats.effect.Timer
-import cats.effect.concurrent.Ref
 import cats.effect.laws.util.TestContext
 import com.ocadotechnology.sttp.oauth2.ClientCredentialsToken.AccessTokenResponse
 import com.ocadotechnology.sttp.oauth2.Secret
@@ -15,11 +12,12 @@ import org.scalatest.Assertion
 
 import scala.concurrent.duration._
 import com.ocadotechnology.sttp.oauth2.AccessTokenProvider
+import cats.effect.{ Ref, Temporal }
 
 class CachingAccessTokenProviderSpec extends AnyWordSpec with Matchers {
   implicit lazy val testContext: TestContext = TestContext.apply()
   implicit lazy val cs: ContextShift[IO] = IO.contextShift(testContext)
-  implicit lazy val ioTimer: Timer[IO] = testContext.timer[IO]
+  implicit lazy val ioTimer: Temporal[IO] = testContext.timer[IO]
 
   private val testScope: Option[Scope] = Scope.of("test-scope")
   private val token = AccessTokenResponse(Secret("secret"), None, 10.seconds, testScope)
diff --git a/oauth2-cache-ce2/src/test/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CatsRefExpiringCacheSpec.scala b/oauth2-cache-ce2/src/test/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CatsRefExpiringCacheSpec.scala
index 9ae0cae5..49ab85e1 100644
--- a/oauth2-cache-ce2/src/test/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CatsRefExpiringCacheSpec.scala
+++ b/oauth2-cache-ce2/src/test/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/CatsRefExpiringCacheSpec.scala
@@ -1,18 +1,17 @@
 package com.ocadotechnology.sttp.oauth2.cache.ce2
 
 import cats.effect.Clock
-import cats.effect.ContextShift
 import cats.effect.IO
-import cats.effect.Timer
 import cats.effect.laws.util.TestContext
 import org.scalatest.matchers.should.Matchers
 import org.scalatest.wordspec.AnyWordSpec
 import scala.concurrent.duration._
+import cats.effect.Temporal
 
 class CatsRefExpiringCacheSpec extends AnyWordSpec with Matchers {
   implicit lazy val testContext: TestContext = TestContext.apply()
   implicit lazy val cs: ContextShift[IO] = IO.contextShift(testContext)
-  implicit lazy val ioTimer: Timer[IO] = testContext.timer[IO]
+  implicit lazy val ioTimer: Temporal[IO] = testContext.timer[IO]
 
   private val someKey = "key"
   private val someValue = 1
diff --git a/oauth2-cache-ce2/src/test/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/TestAccessTokenProvider.scala b/oauth2-cache-ce2/src/test/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/TestAccessTokenProvider.scala
index 376c657a..ae5816ef 100644
--- a/oauth2-cache-ce2/src/test/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/TestAccessTokenProvider.scala
+++ b/oauth2-cache-ce2/src/test/scala/com/ocadotechnology/sttp/oauth2/cache/ce2/TestAccessTokenProvider.scala
@@ -1,13 +1,13 @@
 package com.ocadotechnology.sttp.oauth2.cache.ce2
 
 import cats.Functor
-import cats.effect.concurrent.Ref
 import cats.syntax.all._
 import com.ocadotechnology.sttp.oauth2.ClientCredentialsToken
 import com.ocadotechnology.sttp.oauth2.Introspection
 import com.ocadotechnology.sttp.oauth2.Secret
 import com.ocadotechnology.sttp.oauth2.common.Scope
 import com.ocadotechnology.sttp.oauth2.AccessTokenProvider
+import cats.effect.Ref
 
 trait TestAccessTokenProvider[F[_]] extends AccessTokenProvider[F] {
   def setToken(scope: Option[Scope], token: ClientCredentialsToken.AccessTokenResponse): F[Unit]