Abstract This work aims to identify the best treatment condition for removal of chemical oxigen demand (COD) and increase of biodegradability in an advanced oxidative process of photocatalytic ozonation with titanium dioxide (TiO2), applied to the remediation of the leachate produced at the municipal landfill of Campo Mourão, Paraná. The experiment was carried out using a photocatalytic chamber and an ozonation system based on the corona effect. A statistical model of the central composite rotatable design (CCRD) was elaborated and three variables (pH, TiO2 dose and airflow) were analyzed, to define the optimum condition that allows the highest perfomance of the treatment. The statistical model was valid for the data. The best condition identified was: pH = 3.3 TiO2 dose = 0.012 g and flow = 9.0 L.min-1 (8.79 g, O3.min-1). The removal of filtrate COD was approximately 30% and increase in biodegradability (BOD/COD) = 0.59 in the optimum condition. Factors such as the complex composition of the leachate and treatment time were considered as possible limitants for better results. The treatment did not allow to reach the permissible limits for disposal of the effluent at the environment, in Brazil.