The thermal decomposition of Mn(II) dicarboxylate anhydride Mn[OOC(CH2)(n)COO] (n = 0, 1-8) was studied using simultaneous non-isothermal techniques (TG and DTA). It was shown that CO2 has an inhibiting effect on the decomposition whereas air has an accelerating effect, both relative to Ar. The final products are MnO in Ar and CO2, and Mn3O4 in air, as characterized by chemical analysis, IR spectroscopy and XRD measurements. In general the initial decomposition temperatures in Ar were found to decrease with increasing number of CH2 groups.