A nonalternating 1:3 maleic acid-methyl methacrylate copolymer was synthesized and characterized, and its polyelectrolyte behavior was studied by potentiometric and conductometric titrations, Two intrinsic dissociation constants were found equal to 3.5 and 7.6, and only a slight influence of the nature of the counterions and of the presence of added salt (0.1 M) was observed. The transport coefficients, determined from conductometry, for mono- and divalent cations were in relatively good agreement with the values calculated from Manning theory, especially at low polymer concentrations. A conformational change around alpha(N) similar to 0.25 was confirmed by means of viscometric and fluorescence measurements.