A new 1-dimensional polymeric manganese molybdenophosphate, [(CH 3 ) 4 N][Mn 2 Mo 6 O 1 2 (OH) 4 (PO 4 )(HPO 4 )(H 2 PO 4 ) 2 ].4H 2 O has been prepared hydrothermally. It crystallises in the triclinic system, P-1, with a = 12.583(4), b = 14.322(4), c = 12.365(5) , α = 104.70(3)°, β = 117.02(3)° and γ 85.14(3)°. The structure is based on the [Mo 6 O 1 2 (OH) 3 (H x PO 4 ) 4 ] n - anion previously observed in several other molybdenophosphates. These units are linked together by two different manganese-containing layers into infinite anionic chains, which are linked together only by intervening TMA cations and H-bonds.