BACKGROUND: The Taguchi method, a powerful tool for the optimization of quality, was used to improve the yield of thiocarbohydrazide in its synthetic process. An orthogonal array was selected to analyze the effects of the process factors, i.e. reflux time, molar ratio of hydrazine to carbon disulfide and reflux temperature. Experiments were undertaken to confirm the effectiveness of the Taguchi method. RESULTS: Through this study, the main factors that affect the yield of thiocarbohydrazide were found, together with the optimal factor levels. It was shown that the reflux temperature was the most significant factor affecting the yield of thiocarbohydrazide, followed by the molar ratio of hydrazine to carbon disulfide. The optimum factor levels were a reflux time of 6 h, molar ratio of hydrazine to carbon disulfide 3.0 and reflux temperature 70 degrees C. A 92.3% yield of thiocarbohydrazide was obtained at these optimal factor levels. CONCLUSIONS: The yield of thiocarbohydrazide can be significantly improved by optimization of the synthetic process factors. The Taguchi method provided a systematic and efficient methodology for this optimization, with far less effort than would be required for most other optimization techniques. (C) 2010 Society of Chemical Industry