Solid state reactivity between iron/II/oxalate dihydrate, i.e., FeC2O4.2H2O and para-chloro aniline hydrochloride, i.e., p-ClC6H4NH2.HCl has been studied at 373, 393 and 413 K. The reaction seems to follow the diffusion controlled mechanism. The product, [FeCl/oxH/.AN–Cl], has been characterized by elemental analysis, infrared and Mössbauer spectroscopic techniques, mass spectrometry and derivatographic methods /TG, DTA/.