Interpolymer complex formation has been studied between acrylamide-vinyl alcohol graft copolymer, methacrylic acid-acrylamide random copolymer and polyethylene imine. Some blends of binary homopolymer complexes having the same proportion of interacting units as in copolymer complex have also been prepared. Stability constant, degree of linkage and related thermodynamic parameters (e.g. Delta G degrees, Delta H degrees and Delta S degrees) have been compared for the two complexation systems using Osada’s methods. The comparative study indicated considerable difference in the values of these parameters, which has been explained on the basis of copolymer structure.