The work describes the synthesis and characterization of copolymers of methyl methacrylate (MMA) and N-o-tolyl maleimide (MO)/N-p-tolyl maleimide (MP)/4-maleimido benzoic acid (MB). The copolymers were synthesized by Varying the mol fraction of N-aryl maleimides from 0.1 to 0.5 in the initial feed using azobisisobutyronitrile (AIBN) as an initiator and tetrahydrofuran as the solvent. The copolymer composition was determined from the H-1-NMR spectra by taking the ratio of proton resonance signals due to - OCH3 of MMA (delta = 3.59 ppm) and the aromatic protons (delta = 7.0-7.3 ppm) of N-aryl maleimides. The monomer reactivity ratios of MMA-MP were r(1) = 0.926 +/- 0.001 and r(2) = 0.47 +/- 0.03 and MMA-MO were r(1) = 1.37 +/- 0.005 and r(2) = 0.31 +/- 0.01. The initial decomposition temperature of copolymers and glass transition temperatures increased with increasing N-aryl maleimide content in the backbone.