The influence of substrate orientation and dopant on the growth kinetics of Pt2Si and PtSi have been studied. It was found that the growth of both silicides is diffusion limited and independent of substrate orientation. However, on substrates doped with an arsenic concentration of 5×10 20 cm-3 the preexponential factor of the PtSi growth kinetics is lowered by a factor of 2, but the activation energy remains unchanged. This change in the preexponential factor is independent of the Si substrate orientation. The results are discussed in terms of possible diffusion mechanisms in PtSi.