Titanium complexes, such as titanium citrate, tartrate and lactate, reacted with polyacrylamide (PAAm) to form a crosslinked polymer. The crosslinked PAAm film became insoluble in water. Titanium complexes also reacted with water to form partially hydrolyzed titanium complexes which could not act effectively as a crosslinking agent of PAAm at the ordinary temperature. However, the solubility of PAAm film containing the complexes decreased markedly in an aqueous acetic acid solution. The decrease of solubility attributed to the crosslinkage of PAAm with the complexes in the acetic acid solution. Exposure to ultraviolet light increased the solubility of crosslinked PAAm film, and that of PAAm film containing partially hydrolyzed complexes in an aqueous acetic acid solution. The increasing solubility by the exposure is attributed to the photoreduction of Ti (IV) to Ti (III), which led to the degradation of the crosslinkage and to the inactivation of the complexes.