The processing parameters are known to influence the dispersion as well as size of clusters during dispersion of nano fillers in a matrix. To understand the complex interactions among processing parameters and properties of nanocomposites, statistical design of experiment provides techniques that can be used to efficiently explore these interactions. In the present work, epoxy clay nanocomposites which contain 3 wt%, 4 wt% and 5 wt% nanoclay have been synthesized by in-situ polymerization. A systematic study based on Taguchi's design of experiments has been carried out to comprehend the relationships between processing parameters (temperature, impeller speed, ultrasonic mixing time) and tensile properties of epoxy clay nanocomposites. Analysis of variance (ANOVA) and main effect plots have been used to determine the significant parameters and determine the optimal level for each. The analysis reveals that temperature during premixing step is the most significant factor affecting the tensile modulus. Since the viscosity of resin decreases drastically with an increase in temperature, the results suggest that the viscosity should be low during the processing step. Also, it was observed that an increase in ultrasonication time beyond 1 h has a deteriorating effect on all mechanical properties. © 2017 Elsevier Ltd.