Protein solubility stands as a critical functional attribute, particularly for numerous plant proteins which often exhibit lower solubility compared to their animal-derived counterparts. This chapter provides an overview of common techniques employed in the field of food science for soluble protein quantification. Moreover, detailed procedures for two colorimetric methods for protein solubility measurements: Bicinchoninic acid (BCA) and Bradford assays are covered. The typical experimental parameters used for the two assays are also reported. This chapter could be a valuable guideline for obtaining solubility profile of plant proteins.