The thermal decomposition of MnC2O4. 2H(2)O and CdC2O4. H2O have been studied by two probe direct current electrical conductivity measurements under the atmospheres of static air, dynamic dry nitrogen and dynamic air. The products at each decomposition stage have been characterized by infrared spectroscopy and X-ray powder diffraction. The electrical conductivity measurements were found to give additional information on the solid-state reaction as compared to that obtained from conventional thermal analytical techniques (such as TG and DTA).