The electrocatalytic reactions of carbon dioxide that are catalyzed by [Ir-2(dimen)(4)](2+) (dimen = 1,8-diisocyanomethane) were studied with cyclic voltammetry and infrared spectroelectrochemistry. The hexafluorophosphate (PF6-) salt and the tetraphenylborate (B(C6H5)(4)(-)) salt are electrocatalysts for carbon dioxide reduction. Infrared spectroelectrochemisty allowed the identification of the carbon dioxide reduction products and provided information about the mechanism(s) of the reduction. Bicarbonate and formate were identified as the electrocatalytic carbon dioxide reaction products by comparing the infrared bands observed by spectroelectrochemistry with authentic samples of tetrabutylammonium formate, tetrabutylammonium oxalate, and tetrabutylammonium bicarbonate. Formate arises from a net two-electron reduction of carbon dioxide that produces free formate and a formate complex of [Ir-2(dimen)(4)](2+). Bicarbonate results from the reaction of hydroxide (produced when residual water is reduced to hydrogen) with carbon dioxide.