The quantum yield for the reductive elimination of azide from trans-Pt(CN) 4(N 3) 2 2− to yield P-(CN) 4 2− and molecular nitrogen in aqueous solution was studied as a function of pressure up to 200 MPa. The resulting volume of activation of 8.1 ± 0.4 cm 3 mol −1 is interpreted as evidence for the formation of a caged radical species via simultaneous scission of both PtN 3 bonds in the CT excited state. Similar measurements in ethanol result in a volume of activation of 14.3 ± 0.9 cm 3 mol −1. An additional deactivation route for the CT excited state is suggested to account for this result.