Learn how to use DSC to screen for physical stability of proteins in solution. The utility of microcalorimetry as a rapid screening tool for assessing the solution stability of high molecular weight pharmaceutical proteins was evaluated using model recombinant antibodies, Protein I and Protein II. Changes in the transition midpoint, Tm, were monitored as a function of pH and/or in the presence of excipients, and results were compared with traditional accelerated stability data from samples that were analyzed by size exclusion chromatography (SEC). The data from microcalorimetry were well correlated with those from SEC for predicting both optimal solution pH as well as excipient effects on solution stability. These results indicate that microcalorimetry can be an efficient screening tool useful in identifying optimal pH conditions and excipients to stabilize pharmaceutical proteins in solution formulations.