三聚磷酸，又称三磷酸，是一种磷酸缩合而成的多酸，化学式为H₅P₃O₁₀。

三聚磷酸再与一分子磷酸缩合则形成四聚磷酸（H₆P₄O₁₃）。

一些化合物是三聚磷酸的酯，例如ATP（三磷酸腺苷）。

Triphosphoric acid (also tripolyphosphoric acid), with formula H₅P₃O₁₀, is a condensed form of phosphoric acid. In the family of phosphoric acids, it is the next polyphosphoric acid after pyrophosphoric acid, H₄P₂O₇, also called diphosphoric acid.

Compounds such as ATP (adenosine triphosphate) are esters of triphosphoric acid.