diff --git a/CHANGELOG.md b/CHANGELOG.md
index 683c443..e22425c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+### Changed
+- Removed `State` from `EntropyScaling` trait and adjusted associated methods to use temperature, volume and moles instead of state. [#36](https://github.com/feos-org/feos-core/pull/36)
+
 ## [0.1.5] - 2022-02-21
 ### Fixed
 - Fixed bug in `predict` of `Estimator`. [#30](https://github.com/feos-org/feos-core/pull/30)
diff --git a/src/equation_of_state.rs b/src/equation_of_state.rs
index d84d5eb..8590ba5 100644
--- a/src/equation_of_state.rs
+++ b/src/equation_of_state.rs
@@ -1,5 +1,5 @@
 use crate::errors::{EosError, EosResult};
-use crate::state::{State, StateHD};
+use crate::state::StateHD;
 use crate::EosUnit;
 use ndarray::prelude::*;
 use num_dual::{Dual3, Dual3_64, Dual64, DualNum, HyperDual, HyperDual64};
@@ -295,11 +295,26 @@ pub trait EquationOfState {
 }
 
 /// Reference values and residual entropy correlations for entropy scaling.
-pub trait EntropyScaling<U: EosUnit, E: EquationOfState> {
-    fn viscosity_reference(&self, state: &State<U, E>) -> EosResult<QuantityScalar<U>>;
+pub trait EntropyScaling<U: EosUnit> {
+    fn viscosity_reference(
+        &self,
+        temperature: QuantityScalar<U>,
+        volume: QuantityScalar<U>,
+        moles: &QuantityArray1<U>,
+    ) -> EosResult<QuantityScalar<U>>;
     fn viscosity_correlation(&self, s_res: f64, x: &Array1<f64>) -> EosResult<f64>;
-    fn diffusion_reference(&self, state: &State<U, E>) -> EosResult<QuantityScalar<U>>;
+    fn diffusion_reference(
+        &self,
+        temperature: QuantityScalar<U>,
+        volume: QuantityScalar<U>,
+        moles: &QuantityArray1<U>,
+    ) -> EosResult<QuantityScalar<U>>;
     fn diffusion_correlation(&self, s_res: f64, x: &Array1<f64>) -> EosResult<f64>;
-    fn thermal_conductivity_reference(&self, state: &State<U, E>) -> EosResult<QuantityScalar<U>>;
+    fn thermal_conductivity_reference(
+        &self,
+        temperature: QuantityScalar<U>,
+        volume: QuantityScalar<U>,
+        moles: &QuantityArray1<U>,
+    ) -> EosResult<QuantityScalar<U>>;
     fn thermal_conductivity_correlation(&self, s_res: f64, x: &Array1<f64>) -> EosResult<f64>;
 }
diff --git a/src/state/properties.rs b/src/state/properties.rs
index 7bd9bef..e853f12 100644
--- a/src/state/properties.rs
+++ b/src/state/properties.rs
@@ -615,13 +615,15 @@ impl<U: EosUnit, E: EquationOfState> State<U, E> {
 ///
 /// These properties are available for equations of state
 /// that implement the [EntropyScaling] trait.
-impl<U: EosUnit, E: EquationOfState + EntropyScaling<U, E>> State<U, E> {
+impl<U: EosUnit, E: EquationOfState + EntropyScaling<U>> State<U, E> {
     /// Return the viscosity via entropy scaling.
     pub fn viscosity(&self) -> EosResult<QuantityScalar<U>> {
         let s = self
             .molar_entropy(Contributions::Residual)
             .to_reduced(U::reference_molar_entropy())?;
-        Ok(self.eos.viscosity_reference(self)?
+        Ok(self
+            .eos
+            .viscosity_reference(self.temperature, self.volume, &self.moles)?
             * self.eos.viscosity_correlation(s, &self.molefracs)?.exp())
     }
 
@@ -638,7 +640,8 @@ impl<U: EosUnit, E: EquationOfState + EntropyScaling<U, E>> State<U, E> {
 
     /// Return the viscosity reference as used in entropy scaling.
     pub fn viscosity_reference(&self) -> EosResult<QuantityScalar<U>> {
-        self.eos.viscosity_reference(self)
+        self.eos
+            .viscosity_reference(self.temperature, self.volume, &self.moles)
     }
 
     /// Return the diffusion via entropy scaling.
@@ -646,7 +649,9 @@ impl<U: EosUnit, E: EquationOfState + EntropyScaling<U, E>> State<U, E> {
         let s = self
             .molar_entropy(Contributions::Residual)
             .to_reduced(U::reference_molar_entropy())?;
-        Ok(self.eos.diffusion_reference(self)?
+        Ok(self
+            .eos
+            .diffusion_reference(self.temperature, self.volume, &self.moles)?
             * self.eos.diffusion_correlation(s, &self.molefracs)?.exp())
     }
 
@@ -663,7 +668,8 @@ impl<U: EosUnit, E: EquationOfState + EntropyScaling<U, E>> State<U, E> {
 
     /// Return the diffusion reference as used in entropy scaling.
     pub fn diffusion_reference(&self) -> EosResult<QuantityScalar<U>> {
-        self.eos.diffusion_reference(self)
+        self.eos
+            .diffusion_reference(self.temperature, self.volume, &self.moles)
     }
 
     /// Return the thermal conductivity via entropy scaling.
@@ -671,7 +677,9 @@ impl<U: EosUnit, E: EquationOfState + EntropyScaling<U, E>> State<U, E> {
         let s = self
             .molar_entropy(Contributions::Residual)
             .to_reduced(U::reference_molar_entropy())?;
-        Ok(self.eos.thermal_conductivity_reference(self)?
+        Ok(self
+            .eos
+            .thermal_conductivity_reference(self.temperature, self.volume, &self.moles)?
             * self
                 .eos
                 .thermal_conductivity_correlation(s, &self.molefracs)?
@@ -692,6 +700,7 @@ impl<U: EosUnit, E: EquationOfState + EntropyScaling<U, E>> State<U, E> {
 
     /// Return the thermal conductivity reference as used in entropy scaling.
     pub fn thermal_conductivity_reference(&self) -> EosResult<QuantityScalar<U>> {
-        self.eos.thermal_conductivity_reference(self)
+        self.eos
+            .thermal_conductivity_reference(self.temperature, self.volume, &self.moles)
     }
 }