Full factorial design of experiment was used to screen the factors affecting the color and COD removal efficiency for an azo dye, Direct Orange 26 (DO26). The obtained linear model was statistically tested using analysis of variance (ANOVA); Student's t-test, lack of fit test, and test of curvature. The percentage removal of color and COD was examined by varying experimental conditions with center points. The factors and levels used during the experiments were; initial pH (2, 4 and 6), catalyst amount (0.2 g/250 ml, 0.6 g/250 ml and 1g/250 ml), stirring speed (150 rpm, 200 rpm and 250 rpm) and reaction time (10 min., 35 min. and 60 min.). A desirability function based simultaneous optimization procedure was implemented to seek better conditions in terms of maximizing the color and COD removal from wastewaters. The results showed that 98.5% color and 77.5% COD removal was obtained when initial pH, catalyst amount, stirring speed, and reaction time are roughly set to 2, 1 g/250 ml, 250 rpm, and 60 min., respectively.