Various mechanistic schemes for the recombination reaction of rhodopsin were designed and tested using computer modeling and simulation with data from kinetics experiments. The reaction schemes were mathematically modeled by systems of nonlinear first-order ordinary differential equations (ODEs) with unknown rate constants. Each model was fitted to the experimental data by using a modified simplex algorithm for parameter (rate constant) estimation and Gear's method for solving stiff systems of ODEs. The recombination reaction of rhodopsin was best modeled by branched, multistep reaction schemes which included formation of noncovalent complexes, acid-base equilibria, and acid and base-catalyzed dehydration of a Schiff base intermediate. The biochemical bases for these models are discussed.