The excited-state intramolecular proton transfer and following reverse ground-state proton transfer of photoluminescent polyquinoline are investigated by measuring temperature-dependent fluorescence and transient absorption kinetic profiles. The transfer at the lowest excited singlet state takes place within 6 ps via a preexisting intramolecular hydrogen bond with a negligibly small activation energy. On the other hand, the reverse transfer at the ground state occurs in the time scale of 10 mus. The rapid proton transfer cycle of the polymer is of great interest due to its implications for optoelectronic devices such as dye lasers.