An electron microscope study of the morphology of the silver particles forming in the image area from the photothermographic process shows that the shape and size of the silver crystals change depending on the method of preparation of the silver halide/silver fatty acid complex system. In the case of the in situ process, silver halide obtained by treating silver stearate with solutions of brominating agents (LiBr, ZnBr₂, or HgBr₂) during the photothermographic process yields silver filaments. In the case where the silver halide is preformed and then added during the preparation of the silver carboxylate, dendritic silver particles result during the photothermographic process.