The stress evolution during silicide formation from thin metal films on Si substrates is not well understood. It requires a detailed knowledge of the mechanical properties of each substance, i.e. metal, silicide(s) and Si, in the reacting system. In situ curvature measurement generally gives access to the overall force in the layered stack, whereas in situ X-ray diffraction (XRD) provides information about the mechanical strain in each crystalline sublayer. In this study, we performed both in situ XRD and curvature measurements on the Pd/Si(001) system. From both measurements, we found out that the in-plane strain in the metal and in the silicide is compressive. Whereas it decreases all along the solid-state reaction for the silicide, it slightly increases for the metal. We then compared our results with the qualitative model proposed by Zhang and d'Heurle. This model suggests a high compressive stress in the silicide at the very first stage of the reaction. This is in good agreement with our experimental results. Finally, the measured strains were then translated into force per unit width and compared to in-situ curvature measurement results. A good qualitative agreement between these two different measurements was also found.