The thermal degradation behavior of random copolymers of dimethyl itaconate and di-n-butyl itaconate with methyl methacrylate was studied. The thermal stability of copolymers depends on the structure of the di-n-alkyl itaconate comonomer, and on the copolymer composition. The relative thermal stability increases with the methyl methacrylate copolymer molar fraction, following a trend similar to the glass transition temperature variation. The activation energy was obtained by using MacCallum and Tanner's approach. In addition, the thermal degradation of homopolymers was evaluated in inert atmosphere as well as in thermo-oxidative conditions, presenting different behaviors.