Manganese molybdate with the formula Mn2MoO5.0.6H2O 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 (Dm) and calculated density (Dx) are 3.200 and 3.103, respectively.