diff --git a/include/cantera/thermo/Phase.h b/include/cantera/thermo/Phase.h
index 044f37109..7104facfd 100644
--- a/include/cantera/thermo/Phase.h
+++ b/include/cantera/thermo/Phase.h
@@ -655,6 +655,7 @@ public:
     //! \f[ \sum_k Y_k Q_k \f]
     //!     @param[in] Q  Array of species property values in mass units.
     //!     @return The mass-fraction-weighted mean of Q.
+    //! @deprecated Unused. To be removed after Cantera 2.2.
     doublereal mean_Y(const doublereal* const Q) const;
 
     //!  The mean molecular weight. Units: (kg/kmol)
@@ -669,6 +670,7 @@ public:
     //! Evaluate \f$ \sum_k X_k \log Q_k \f$.
     //!     @param Q Vector of length m_kk to take the log average of
     //!     @return The indicated sum.
+    //! @deprecated Unused. To be removed after Cantera 2.2.
     doublereal sum_xlogQ(doublereal* const Q) const;
     //@}
 
diff --git a/src/thermo/Phase.cpp b/src/thermo/Phase.cpp
index d1b0dfd37..b15257542 100644
--- a/src/thermo/Phase.cpp
+++ b/src/thermo/Phase.cpp
@@ -694,6 +694,7 @@ doublereal Phase::mean_X(const vector_fp& Q) const
 
 doublereal Phase::mean_Y(const doublereal* const Q) const
 {
+    warn_deprecated("Phase::mean_Y", "To be removed after Cantera 2.2.");
     return dot(m_y.begin(), m_y.end(), Q);
 }
 
@@ -704,6 +705,7 @@ doublereal Phase::sum_xlogx() const
 
 doublereal Phase::sum_xlogQ(doublereal* Q) const
 {
+    warn_deprecated("Phase::sum_xlogQ", "To be removed after Cantera 2.2.");
     return m_mmw * Cantera::sum_xlogQ(m_ym.begin(), m_ym.end(), Q);
 }