H2S is converted into hydrogen and sulfur using a two-step process. In the first stage, H2S is reacted with an anthraquinone molecule in a polar solvent to produce a hydroanthroquinone and a sulfur precipitate. In the second stage, the solution containing the hydroquinone is passed through a catalyst bed to regenerate the anthraquinone and produce hydrogen gas. The formation of a diradical anthraquinone species is critical in the first step of the reaction sequence. The effect of aromatic ring substituents and solvent effects on the formation of this species are discussed. This is an abstract of a paper presented at the 230th ACS National Meeting (Washington, DC 8/28/2005-9/1/2005).