The objective of the research study was to evaluate the physicochemical properties of commercial powdered protein supplements. The research material consisted of 4 powdered preparations:  soy protein isolate, whey protein concentrate, hemp protein and pea protein concentrate. The research scope included the determination of water content and water activity, static and dynamic  angle of repose, loose and tapped density, colour, and reconstitution and sorption properties of the selected preparations, including specific sorption surface and capacity of the monomolecular  layer. On the basis of the analyses performed, it was found that the products under evaluation were characterised by a different level of water content and water activity, dependent on the  composition of raw material of the powdered protein preparation. The highest values of those parameters were reported for the hemp protein and pea protein concentrate. Based on the  evaluation of the loose and tapped density parameters and static angle of repose, it was found that the powdered proteins tested were characterised by an average cohesiveness and a diverse  flowability. Better physicochemical properties were characteristic for the products of plant origin. By measuring the dynamic angle of repose, it was possible to provide a relationship between  the measuring surface applied and the flowability of the powdered protein tested. It was reported that the whey protein was characterised by the highest storing stability, whilst the hemp protein – by the lowest values of Vm and specific sorption surface. The above described research study helped determine the storing stability of the commercial, powdered protein supplements manufactured industrially and evaluate their initial suitability during the handling or transhipment operations.