Catalytic thermal cracking of O-2 is employed to dope helium droplets with O(P-3) atoms. Mass spectrometry of the doped droplet beam reveals an O-2 dissociation efficiency larger than 60%; approximately 26% of the droplet ensemble is doped with single oxygen atoms. Sequential capture of O(P-3) and HCN leads to the production of a hydrogen-bound O-HCN complex in a (3)Sigma electronic state, as determined via comparisons of experimental and theoretical rovibrational Stark spectroscopy. Ab initio computations of the three lowest lying intermolecular potential energy surfaces reveal two isomers, the hydrogen-bound ((3)Sigma) O-HCN complex and a nitrogen-bound ((3)Pi) HCN-O complex, lying 323 cm(-1) higher in energy. The HCN-O to O-HCN interconversion barrier is predicted to be 42 cm(-1). Consistent with this relatively small interconversion barrier, there is no experimental evidence for the production of the nitrogen -bound species upon sequential capture of O(P-3) and HCN.