The effects of three preparation variables, i.e. reaction temperature, reaction time and reaction gas (methane/nitrogen) flow rate, on the ratio of the intensity of the Raman D band to the intensity of the G band (ID/IG), carbon mass and the presence of radial breathing mode (RBM) peaks were investigated by using a central composite design to develop two linear models. The most influential factor in each experimental design-response was identified using the analysis of variance. The predicted ID/IG ratio, carbon mass and presence of RBM peaks determined during the process optimisation were found to agree satisfactorily with the experimental values. The optimum conditions for synthesising single-walled carbon nanotubes were determined to be a reaction temperature of 900 degrees C, a reaction time of 59?min and a reaction gas flow rate of 54?mL/min. (c) 2011 Canadian Society for Chemical Engineering