Description General description Sodium cacodylate trihydrate is a biological buffer. Its crystals have been analyzed by single-crystal X-ray diffraction studies. Studies suggested its crystals exhibited two phases, viz. penta-μ-aqua-disodium(I) bis(dimethylarsenate), {[Na2(H2O)5](C2H6AsO2)2}n and di-μ-aqua-bis[triaquasodium(I)] bis(dimethylarsenate), [Na2(H2O)8](C2H6AsO2)2. Application Sodium cacodylate trihydrate may be employed as buffer to maintain pH 7.4 in electron microscopic studies. It may be used to compose cacodylate buffer for use in electron microscopic studies.