The inverse microemulsion polymerization of acrylamide in a paraffinic solvent, Rolling-M-245, stabilized by a mixture of nonionic surfactants (Emulan-ELP-11 and Brij-92), was studied. Pseudoternary phase diagrams of this system were determined, and a range of hydrophilic-lipophilic balance (HLB) values, from 8.98 to 9.2, were selected as the most favorable for acrylamide polymerization. The influence of factors such as the initiator composition, HLB, percentage of the aqueous phase, and addition of the monomer by steps on the final conversion and polyacrylamide molar masses were investigated. High conversions and molar masses were generally obtained with the different formulations. The polyacrylamide molar masses were influenced by the HLB and content in the aqueous phase. The addition of the aqueous phase by steps led to a progressive diminution of the molar masses as the number of stages increased. (c) 2005 Wiley Periodicals, Inc.