Abstract: A method is provided for the production and purification of carboxylic betaine-based zwitterionic vinyl monomers, such as (meth)acrylic or (meth)acrylamide monomer containing a betaine-type group of the formula: wherein A is an ester, amide, benzyl, pyridinyl, or imidazolyl; R is hydrogen or methyl; and n is an integer from 0 to 10. The method involves the reaction of acrylic acid with aminoalkyl (meth)acrylate or N-amino-alkyl (meth)acrylamide having a basic tertiary nitrogen atom in the presence of a free radical inhibitor, this reaction leads to a betaine:acid complex that can be either separated from the reaction media into pure betaine:acid complex powder or further purified into pure monomer powder by passing the reaction mixture through a base resin followed by precipitation in a nonsolvent or direct precipitation in a nonsolvent containing an organic base.