A sandwich-type rhodium polyoxotungstate with unprecedented tetrarhodium-oxo core Na(12)[(Rh(4)(μ(3)-O)(2)(H(2)O)(2))(H(2)W(9)O(33))(2)]·38H(2)O (1) was obtained by hydrothermal reaction of rhodium(II) acetate and sodium tungstate; crystal structure was determined by X-ray diffractometry and was confirmed by (183)W NMR data; 1 is active in electrocatalytic water oxidation.