Solubility tests have been conducted on hydrolyzed polyacrylamide (PAAm) polymers to define the pH range for solubility as a function of the salinity of the solutions. These tests show for the first time that pH is a critical variable determining the solubility of extensively hydrolyzed PAAm in brines containing divalent cations. The pH range for solubility of PAAm and an acrylamide copolymer as a function of aging in synthetic seawater at elevated temperature is also reported. The underlying mechanisms for the pH-dependent solubility behavior observed and the implications for petroleum applications of acrylamide polymers are discussed.