The first example of Rh-substituted organic-inorganic hybrid arsenotungstate [H2N(CH3)2]8{[Na(H2O)4]NaAs2W22(CH3COO)2O76 Rh2(N(CH3)2)2}·H2O (1) synthesised in an aqueous solution by the conventional method is reported. Two [Rh(N(CH3)2)]3+ fragments are imbedded into the vacancy of the [NaAs2W22(CH3COO)2O76]15- unit by Rh-As bonds [2.439(1) Å], which are observed in POM chemistry for the first time.