Rabbit immunoglobulin G (RIgG) was reduced with dithioerythritol and analyzed by high performance liquid chromatography. A quantitative method for determining the percentage of reduced half-molecules in the mixture was developed. An acetic acid concentration-dependent rate of dissociation of reduced half-molecules was observed. The specific optical absorptivity was determined for whole molecules and half-molecules and found to be significantly greater for the half-molecules. Purified half-molecules were reconstituted into RIgG with a yield greater than 90% following a 16 h incubation at pH 8.0 and room temperature.