A single-site chromium catecholate POP (catPOP A 2 B 1 ) was synthesized and characterized via AT-IR, XAS, and EPR spectroscopy. The well-defined, fourcoordinate, 11-electron Cr(III) centers bound to catecholate POP were demonstrated to be active hydrogenation catalysts for nonpolar unsaturated organic substrates under mild conditions (5 mol % of Cr, 200 psi of H 2 , 60 °C). This material constitutes the first example of a well-defined, supported organometallic chromium hydrogenation precatalyst.