Gas phase and surface kinetic models describing the growth of InP by metallorganic chemical vapor deposition (MOCVD) using trimethylindium and phosphine diluted in hydrogen have been developed. A realistic model of the process was obtained by incorporating the kinetics into a two-dimensional transport model of the flaw, heat, and mass transfer in the horizontal MOCVD reactors. The unknown rate parameters of two surface growth reactions were estimated by comparing predicted growth rates of InP with the ones obtained from an atmospheric-pressure horizontal MOCVD reactor during heteroepitaxy of InP on GaAs. Sensitivity analysis of the reactions led to a reduced kinetic scheme, which call be used for predicting film growth rates with the same accuracy as a more detailed kinetic model, but with smaller computational requirements. The reduced kinetic model was subsequently tested against three sets of InP growth data reported in the literature and it successfully predicted observed growth rates and trends. Finally, parametric studies were performed on the computer to investigate the effects of changing the inlet velocity of the carrier gas, the operating pressure, and the inlet mole fraction of trimethylindium on the growth rate of the films. The proposed model may become a useful tool for reactor design, optimization, and scale-up of InP MOCVD.