Thermal dehydration process of calcium oxalate monohydrate, CaC2O4 center dot H2O, was reinvestigated from a viewpoint of reaction kinetics. On the basis of data of thermogravimetry, kinetic analysis was performed under nonisothermal conditions using an integral composite procedure, which includes a integral isoconversional method and an integral master plots method. The results of the integral isoconversional method of TGA data at various heating rates suggested that dehydration of CaC2O4 center dot H2O followed a single step with an activation energy of 99.02 +/- 2.61 kJ/mol, and from the master plots method, the reaction was described by an R,, model. Finally, it was estimated that the pre-exponential factor A = (2.82 +/- 1.81) X 10(9) s(-1), and the kinetic exponent n = 2.3 +/- 0.2. The results of nonisothermal kinetic analysis of the thermal dehydration reactions of CaC2O4 center dot H2O suggested that the integral composite procedure be very successful in evaluating kinetic parameters and describing kinetic model of solid-state reactions. (c) 2006 American Institute of Chemical Engineers