The kinetics of the reaction of CN radical with fulminic acid (HCNO) was studied by transient infrared absorption spectroscopy with the primary goal of resolving whether the dominant product channel is NO + HCCN (1a) or HCN + NCO (1b). HCN, HCCN, and NO reaction products were directly detected. In some experiments, (NO)-N-15-O-18 reagent was included in the reaction mixtures in order to suppress possible secondary chemistry due to NCO radicals. Several other possible secondary reactions were also investigated and found to be very slow. The resulting product branching fractions of phi(1a) = 0.98 +/- 0.07 for NO + HCCN and phi(1b) <= 0.07 for HCN + NCO, respectively, were obtained at 298 K. The potential energy surface (PES) of the reaction was calculated by ab initio methods at several levels of coupled-cluster theory. The calculations show pathways to channels (1a) and (1b) with nearly identical energetics and a substantial dependence on the level of theory used, suggesting that multireference calculations are needed to accurately predict the experimental results.