This paper presents the results of a theoretical study of the plasma‐activated chemical vapor deposition (PCVD) process used for the preparation of optical fibers. We show how the static deposition profile of silica can be computed by taking into account convection, reaction, and diffusion processes inside the glass tube. The parameters describing these processes are estimated. We examine how the deposition profile depends on the gas velocity, the reaction, and the diffusion constants. Theory and experiment are in good agreement. The calculations confirm the idea that in the PCVD process the deposit is formed from single molecules and not from clusters.