Manganese molybdate with the formula Mn 2 MoO 5 .0.6H 2 O was synthesized by hydrothermal reaction at 200 °C. The crystal system of this compound is triclinic, space group P −1, Z =1, unit-cell parameters: a =5.7769(5), b =9.7559(6), c =2.8961(2), α =94.37(1), β =101.37(1), and γ =94.75(1). The measured density ( D m ) and calculated density ( D x ) are 3.200 and 3.103, respectively.