The potential energy surface (PES) for the losses of CO and HCN from the 3-hydroxypyridine radical cation (3-HP(+•)) and for the isomerizations to 2- and 4-HP(+•) was determined from G3//B3LYP calculations. The overall activation energies are similar for six dissociation channels to form the radical cations of CH(2)=CHCH=N=CH, 1-H, 2-H, and 3-H pyrrole by the loss of CO and to form the radical cations of CH(2)=CHCH=C=O and furan by the loss of HCN. A kinetic analysis based on the obtained PES shows that the acyclic C(4)H(5)N(+•) and C(4)H(4)O(+•) ions are the main products formed by the losses of CO and HCN, respectively.