In the present study statistical tool Response Surface Methodology – Central composite Design (RSM-CCD) were applied to optimize process parameters for the removal of dye Congo red using Nano zero-valent iron (NZVI) impregnated cashew nut shell (NZVI-CNS). Central composite Design (RSM-CCD) design was used to optimize the effect of process variables on the removal of Congo red dye. The NZVI-CNS prepared by simple liquid-phase reduction method, namely, borohydride reduction method. The results of RSM-CCD method showed the significant effect of pH (A), Dose (B), initial concentration (C), time (D), and temperature (E) on Congo red dye removal from aqueous solution. The results of ANOVA and regression of second order model showed that the linear effects of Dose (B) and Temperature (E) were more significant. All the critical variables having greatest effect on the removal of Congo red dye from Nano zerovalent iron impregnated cashew nut shell. Thus the obtained nano zerovalent iron impregnated cashew nut shell successfully employed to remove Congo red dye from aqueous solution. The factors optimized in the present work would helpful in Congo red removal from aqueous solution.