Trisodium phosphate, available at most hardware stores in white powder form, is a cleaning agent and degreaser , commonly used to prepare surfaces for painting (household), sold as 'TSP'. It can also be called trisodium orthophosphate and has the chemical formula Na₃PO₄. It is a highly water-soluble ionic salt. Solutions of it dissolved in water have an alkaline pH.

It can also be found as a food additive: buffer agent, emulsifier, nutrition enlargement agent and metal-chelating agent. In these uses it may be known as simply sodium phosphate.