High molecular weight acrylamide (AAM, Ml)-co-2-acrylamido-2-methyl propane sulfonic acid (AAMPS, M2) copolymers were obtained by plasma-initiated copolymerization in water solutions. The reactivity ratios, determined by Kelen-Tudos method, were shown to be r1 = 1.04 and r2 = 0.41. Some microstructural aspects of the obtained copolymers are presented. in order to test a special use (mobility control in polymer flooding technology), the rheological and thermal behaviour were investigated.