diff --git a/Source/cons.f90 b/Source/cons.f90
index 726a8739294..f25bcba3016 100644
--- a/Source/cons.f90
+++ b/Source/cons.f90
@@ -267,7 +267,7 @@ MODULE GLOBAL_CONSTANTS
 LOGICAL :: SMOKE3D_16=.FALSE.                       !< Output 3D smoke values using 16 bit integers
 LOGICAL :: CHECK_BOUNDARY_ONE_D_ARRAYS=.FALSE.      !< Flag that indicates that ONE_D array dimensions need to be checked
 LOGICAL :: TENSOR_DIFFUSIVITY=.FALSE.               !< If true, use experimental tensor diffusivity model for spec and tmp
-LOGICAL :: TEST_CHAR_MASS_TRANSFER_MODEL=.FALSE.    !< Experimental flag to test mass transfer resistence in char model
+LOGICAL :: OXPYRO_MODEL=.FALSE.                     !< Flag to use oxidative pyrolysis mass transfer model
 LOGICAL :: OUTPUT_WALL_QUANTITIES=.FALSE.           !< Flag to force call to WALL_MODEL
 
 INTEGER, ALLOCATABLE, DIMENSION(:) :: CHANGE_TIME_STEP_INDEX      !< Flag to indicate if a mesh needs to change time step
diff --git a/Source/read.f90 b/Source/read.f90
index 52b3f82a341..2c76a66cbb9 100644
--- a/Source/read.f90
+++ b/Source/read.f90
@@ -1741,7 +1741,7 @@ SUBROUTINE READ_MISC
                 POROUS_FLOOR,PR,PROFILING,&
                 P_INF,RAMP_GX,RAMP_GY,RAMP_GZ,RESTART,RESTART_CHID,SC,&
                 RND_SEED,SHARED_FILE_SYSTEM,SIMULATION_MODE,SMOKE3D_16,SMOKE_ALBEDO,SOLID_PHASE_ONLY,SOOT_DENSITY,SOOT_OXIDATION,&
-                TAU_DEFAULT,TENSOR_DIFFUSIVITY,TERRAIN_IMAGE,TEST_CHAR_MASS_TRANSFER_MODEL,TEXTURE_ORIGIN,&
+                TAU_DEFAULT,TENSOR_DIFFUSIVITY,TERRAIN_IMAGE,TEXTURE_ORIGIN,&
                 THERMOPHORETIC_DEPOSITION,THERMOPHORETIC_SETTLING,THICKEN_OBSTRUCTIONS,&
                 TMPA,TURBULENCE_MODEL,TURBULENT_DEPOSITION,UVW_FILE,&
                 VERBOSE,VISIBILITY_FACTOR,VN_MAX,VN_MIN,Y_CO2_INFTY,Y_O2_INFTY,&
@@ -6133,6 +6133,7 @@ SUBROUTINE PROC_PART
 TYPE(LAGRANGIAN_PARTICLE_CLASS_TYPE), POINTER :: LPC=>NULL()
 TYPE(SPECIES_TYPE),POINTER:: SS=>NULL()
 TYPE(SURFACE_TYPE),POINTER:: SF=>NULL()
+TYPE(MATERIAL_TYPE), POINTER :: ML=>NULL()
 
 IF (N_LAGRANGIAN_CLASSES == 0) RETURN
 
@@ -6152,7 +6153,7 @@ SUBROUTINE PROC_PART
       LPC%FTPR = FOTH*PI*LPC%DENSITY
    ENDIF
 
-   IF (SF%THERMAL_BC_INDEX==THERMALLY_THICK) THEN
+   THERMALLY_THICK_IF: IF (SF%THERMAL_BC_INDEX==THERMALLY_THICK) THEN
       LPC%INCLUDE_BOUNDARY_ONE_D_TYPE = .TRUE.
       MASS = 0._EB
       VOLUME = 0._EB
@@ -6182,8 +6183,14 @@ SUBROUTINE PROC_PART
       LPC%INITIAL_MASS = MASS
       LPC%FTPR = FOTH*PI*LPC%DENSITY
 
-      IF (TEST_CHAR_MASS_TRANSFER_MODEL) LPC%INCLUDE_BOUNDARY_PROP2_TYPE = .TRUE.
-   ENDIF
+      ! Set up oxidative pyrolysis mass transfer model for thermally thick particles
+
+      DO NN=1,SF%N_MATL
+         ML => MATERIAL(NN)
+         IF ( ANY(ML%N_O2>0._EB) ) OXPYRO_MODEL = .TRUE.
+      ENDDO
+
+   ENDIF THERMALLY_THICK_IF
 
    ! Exclude some convective heat transfer models from being applied to a particle
 
@@ -6259,6 +6266,10 @@ SUBROUTINE PROC_PART
 
 ENDDO PART_LOOP
 
+! If we use OXPYRO_MODEL, allocate necessary boundary information for all particle classes
+
+IF (OXPYRO_MODEL) LAGRANGIAN_PARTICLE_CLASS(1:N_LAGRANGIAN_CLASSES)%INCLUDE_BOUNDARY_PROP2_TYPE = .TRUE.
+
 END SUBROUTINE PROC_PART
 
 
@@ -9423,6 +9434,8 @@ SUBROUTINE PROC_WALL
             ENDIF
          ENDDO
          DENSITY_MIN = MIN(DENSITY_MIN,ML%RHO_S)
+         ! Set up oxidative pyrolysis mass transfer model for thermally thick solids
+         IF ( ANY(ML%N_O2>0._EB) ) OXPYRO_MODEL = .TRUE.
       ENDDO
 
       SF%SWELL_RATIO = 1._EB
diff --git a/Source/wall.f90 b/Source/wall.f90
index ecec1d3a324..9f027b0f27e 100644
--- a/Source/wall.f90
+++ b/Source/wall.f90
@@ -1875,7 +1875,7 @@ SUBROUTINE SOLID_HEAT_TRANSFER(NM,T,DT_BC,PARTICLE_INDEX,WALL_INDEX,CFACE_INDEX,
    LP => LAGRANGIAN_PARTICLE(PARTICLE_INDEX)
    ONE_D => BOUNDARY_ONE_D(LP%OD_INDEX)
    B1 => BOUNDARY_PROP1(LP%B1_INDEX)
-   IF (TEST_CHAR_MASS_TRANSFER_MODEL) B2 => BOUNDARY_PROP2(LP%B2_INDEX)
+   IF (OXPYRO_MODEL) B2 => BOUNDARY_PROP2(LP%B2_INDEX)
    BC => BOUNDARY_COORD(LP%BC_INDEX)
    SURF_INDEX = LAGRANGIAN_PARTICLE_CLASS(LP%CLASS_INDEX)%SURF_INDEX
    SF => SURFACE(SURF_INDEX)
@@ -2857,7 +2857,7 @@ SUBROUTINE PERFORM_PYROLYSIS
 
 ! Initialize parameters for oxidative pyrolysis mass transfer model
 
-IF (TEST_CHAR_MASS_TRANSFER_MODEL) THEN
+IF (OXPYRO_MODEL) THEN
    MAX_ITER=20
    Y_O2_G  = Y_O2_F
    Y_LOWER = 0._EB
@@ -2935,7 +2935,7 @@ SUBROUTINE PERFORM_PYROLYSIS
    ENDDO POINT_LOOP1
 
    !======== Mass transfer resistance to surface O2 concentration =============
-   CHAR_MASS_TRANSFER_MODEL_IF: IF (TEST_CHAR_MASS_TRANSFER_MODEL) THEN
+   OXPYRO_MODEL_IF: IF (OXPYRO_MODEL) THEN
       ! Solve for Y_O2_F using bounded Newton method
       M_DOT_ERROR_OLD = M_DOT_ERROR
       M_DOT_O2_PP = DOT_PRODUCT(Z2Y(O2_INDEX,1:N_TRACKED_SPECIES),M_DOT_G_PP_ACTUAL(1:N_TRACKED_SPECIES))
@@ -2962,7 +2962,7 @@ SUBROUTINE PERFORM_PYROLYSIS
          Y_O2_F = 0.5_EB*(Y_LOWER+Y_UPPER)
       ENDIF
       DY = Y_O2_F - Y_O2_F_OLD
-   ENDIF CHAR_MASS_TRANSFER_MODEL_IF
+   ENDIF OXPYRO_MODEL_IF
    !===========================================================================
 
 ENDDO O2_LOOP