Applicability of a one‐dimensional reaction‐diffusion model (ORDM) as a tool for analyzing the gas–solid phase transition rate process during chemical vapor deposition is tested by comparing its results with those predicted by a simple Monte Carlo method. The results reveal that the ORDM is applicable when the conditions of Knudsen number (Kn)<0.03, aspect ratio (As)≳1.0, and reactive sticking coefficient (&eegr;)<0.1 are fulfilled. At large Kn and large &eegr;, the ORDM gives quite an erroneous result. The ORDM is also applicable to predict the grown film shape when &eegr;<0.1, Kn ≫1.0, and As≳2.0. ©1995 American Institute of Physics.