diff --git a/ExampleCodes/SUNDIALS/Reaction-Diffusion/Exec/inputs_sundials_mri b/ExampleCodes/SUNDIALS/Reaction-Diffusion/Exec/inputs_sundials_mri
index 96860e0d..19e147d2 100644
--- a/ExampleCodes/SUNDIALS/Reaction-Diffusion/Exec/inputs_sundials_mri
+++ b/ExampleCodes/SUNDIALS/Reaction-Diffusion/Exec/inputs_sundials_mri
@@ -1,4 +1,11 @@
 ##
+# Theoretical forward euler explicit time step constraint for each process is based 
+# on the diffusion and reaction coefficients.
+# For diffusion term
+# dt < dx^2 /(2*DIM*diffusion_coef) = (1/32)^2/(2*3*1) = 1.63e-4
+# For reaction term
+# dt <= 2/reaction_coef
+
 n_cell = 32
 max_grid_size = 16