  We develop mixed finite element methods for nonlinear reaction-diffusion
equations with interfaces which have Robin-type interface conditions. We
introduce the velocity of chemicals as new variables and reformulate the
governing equations. The stability of semidiscrete solutions, existence and the
a priori error estimates of fully discrete solutions are proved by fixed point
theorem and continuous/discrete Gr${\"o}$nwall inequalities. Numerical results
illustrating our theoretical analysis are included.
