The end group analysis both for polyacrylamides and polyacrylonitriles initiated by Ce(IV) malonic acid, tartaric acid and citric acid redox systems was carried out by using conductometric titration. Carboxyl end groups of these polymers are determined by dissolving polyacrylamides in water, polyacrylonitriles in dimethylformamide and ethylene carbonate propylene carbonate (80/20 by weight) at 25-degrees and titrating with aqueous sodium hydroxide, alcoholic sodium hydroxide and tetrabutylammonium hydroxide, respectively. The number average molecular weight results are compared with the viscometric ones. It was found that these are in good agreement with each other. In addition to the experiments with conductometric titrations, calculations were made to find the ionization constant of carboxylic acid end groups in acrylamide and acrylonitrile polymers. For this purpose the Ostwald dilution law was used.