The thermal investigation of the reaction taking place between dichromates and oxalates in the solid state has been done taking two systems of potassium dichromate-potassium oxalate and sodium dichromate-sodium oxalate. The techniques employed include thermogravimetry, differential thermal analysis, infrared spectroscopy and X-ray diffraction studies. The results indicate a stoichiometric reaction of dichromate and oxalate in 1:1 ratio to give the corresponding chromate as the sole product. © 1989 Wiley Heyden Ltd., Chichester and Akadémiai Kiadó, Budapest.