Using the micro-Raman technique we recorded the resonance Raman (RR) spectra of an I-/I-3(-)-containing solid electrolyte prepared via the sol-gel technique (ormolyte) that was encapsulated in a solid-state dye-sensitized photoelectrochemical cell (DS PEC). The laser light (514.5 and 488.0 nm), which was used for the excitation of the RR spectra, also acted as an illumination source, making it possible to record the in situ RR spectra of the DS PEC under open- and short-circuit conditions. The RR bands of I-3(-) (111, 141 cm(-1)) and an iodine-solid-electrolyte complex (166 cm(-1) ) served as a probe to follow the changes of the redox components during the operation of the DS PEC, which was illuminated continuously with laser light. Cycling of the DS PEC under open- and short-circuit conditions revealed that KI crystallizes in the solid electrolyte, as was also demonstrated with energy dispersive X-ray measurements. DS PECs employing solid electrolyte with added KI + I-2 exhibited a higher cycling stability than the cells with the electrolytes containing LiI + I-2,CsI + I-2 or tetramethylammonium iodide + I-2.