Single-crystals of manganese hydroxide hydrogen vanadate divanadate, Mn 6.75 (OH) 3 H 1.20 (VO 4 ) 4-2 z (V 2 O 7 ) z ( z = 0.15), have been synthesized hydrothermally. Its hexagonal crystal structure, sp. gr. P 6 3 mc , related to mineral ellenbergerite, has been determined by single-crystal X-ray diffraction. It features a three-dimensional framework of vertex- and face-sharing Mn 2+ -centered octahedra with defective Mn 2+ -octahedral chains and disordered V 2 O 7 , HVO 4 and H 2 VO 4 groups located in hexagonal and triangular type channels. The presence of these groups has been confirmed by Fourier transform infrared spectroscopy. According to magnetization and specific heat data, Mn 6.75 (OH) 3 H 1.20 (VO 4 ) 4-2 z (V 2 O 7 ) z ( z = 0.15) experiences ordering into a canted antiferromagnetic state at T N = 42.5 K. We report on the structural features of Mn 6.75 H 1.20 (VO 4 ) 4-2z (V 2 O 7 ) z ( z = 0.15), which clarified the mechanism of negative charge compensation of the framework. The compound undergoes phase transition at T N = 42.5 K into canted AF state.