The free-radical initiated synthesis of acrylamide-co-2-acrylamido-2-methyl-1-propane sulphonic acid (AAm-co-AMPS) was studied at 60 and 25 degrees C. The monomer reactivity ratios were evaluated using Fineman-Ross and Kelen-Tudos methods, based on elemental analysis of the copolymers and C-13-NMR experimental data. The detailed copolymer microstructure was derived from reactivity ratios using the conditional probability based on the terminal kinetic model for free-radical polymerization. The homopolymers and copolymers were characterized using H-1- and C-13-NMR, and Fourier transform infrared (FTIR) spectroscopic methods, and differential scanning calorimetry. (C) 2000 John Wiley & Sons, Inc.