Phosphoric acid, yomwe imadziwikanso kuti orthophosphoric acid, ndi asidi omwe amagwiritsidwa ntchito m'mafakitale osiyanasiyana. Ili ndi acidity yolimba kwambiri, mankhwala ake ndi H3PO4, ndipo molekyulu yake ndi 97.995. Mosiyana ndi zidulo zina zosasunthika, phosphoric acid ndi yokhazikika ndipo sichiwonongeka mosavuta, ndikupangitsa kukhala chisankho chodalirika cha ntchito zosiyanasiyana. Ngakhale kuti phosphoric acid siili yolimba ngati hydrochloric, sulfuric, kapena nitric acids, ndi yamphamvu kuposa acetic ndi boric acid. Kuphatikiza apo, asidiyu ali ndi zinthu zambiri za asidi ndipo amachita ngati tribasic acid yofooka. Ndikoyenera kudziwa kuti phosphoric acid ndi hygroscopic ndipo imatenga chinyezi kuchokera mumlengalenga. Kuphatikiza apo, imatha kusintha kukhala pyrophosphoric acid ikatenthedwa, ndipo kutayika kwamadzi kotsatira kumatha kusinthira kukhala metaphosphoric acid.