Sodium pyrosulfate is an inorganic compound with the chemical formula of Na<sub>2</sub>S<sub>2</sub>O<sub>7</sub>. It is a colorless salt. It hydrolyses in water to form sodium bisulfate with a chemical formula of NaHSO<sub>4</sub> which has a pH of around 1.
Sodium pyrosulfate is obtained by heating sodium bisulfate to 280 ðC (536 ðF)
Temperatures above 460 ðC further decompose the compound, producing sodium sulfate and sulfur trioxide:
Sodium pyrosulfate was used in analytical chemistry. Samples are fused with sodium pyrosulfate to ensure complete dissolution before a quantitative analysis.