Photodissociation (PD) spectroscopy of protonated guanosine monophosphate (GMPH(+)) ions was performed using IR-laser ablation of droplet beam and quadruple ion trap techniques. Photofragmentation of GMPH(+) gave a protonated guanine ion (GH(+)) as the main product. A wide-range PD spectrum (3.9-5.4 eV) monitored by the GH(+) ion intensity showed four characteristic electronic transitions related to their three different anti glycosyl-bond conformers of GMPH(+) which were identified by their pi-pi* transitions based on time dependent density functional theory calculation. Furthermore, the narrow-bandwidth PD spectrum (4.28-4.33 eV) shows the existence of syn glycosyl-bond conformation with keto form.