The photocatalytic decomposition of acetic acid-containing wastewater was assessed for the removal of pollutants and the production of hydrogen. The effects of irradiation of the liquid phase plasma were evaluated in the photocatalytic decomposition reaction. The evolution of hydrogen was also characterized by the photocatalytic decomposition of wastewater. Ni-loaded TiO2 photocatalysts were introduced to the photocatalytic reaction. With the Ni loading to the TiO2, the adsorption wavelength was enlarged to the visible range. The photochemical decomposition by irradiation of the liquid phase plasma without photocatalysts produced some hydrogen evolution with the degradation of acetic acid, which was attributed to the decomposition of the reactant by active species generated by the irradiation of liquid phase plasma. The rate of hydrogen evolution from water on the photocatalyst was ca. 1.6 mmol/min at 1 h of process time. The photocatalytic decomposition of acetic acid was improved by the addition of Ni-loaded TiO2 photocatalysts by the irradiation of liquid phase plasma. The Ni loading on TiO2 brought out an enhancement of acetic acid degradation and hydrogen evolution. Hydrogen evolution was accelerated significantly due to the additional hydrogen production by the photocatalytic decomposition of acetic acid.