Translational spectroscopy hits been used to study the dissociation of HOCO and DOCO to both the OH/OD((X) over tilde (2)Pi) + CO((X) over tilde (1 Sigma+)) and H/D(S-2) + CO2((X) over tilde (1 Sigma+)) product channels upon charge exchange between a fast (keV) beam of HCCO+/DOCO+ and cesium. Analysis of the measured kinetic energy release distributions for the two product channels Suggests that HOCO is initially produced in the 1(2)A '' electronic state by near resonant electron capture from cesium (similar to 4.31 eV above the ground state trans-HOCO conformer). This initial state undergoes rapid predissociation leading to OH + CO and H + CO2 products, with respective branching fractions of 0.75 +/- 0.03 and 0.25 +/- 0.03. Possible mechanisms leading to dissociation and the observed dissociation dynamics are presented in light of theoretical studies of the low-lying electronic states of HOCO.