Abstract A new one-pot, multicomponent condensation reaction of aldehydes, 2-naphthol, and 1-acylthiosemicarbazides is described as an efficient method for the synthesis of novel 4-substituted 1-acylthiosemicarbazides in the presence of p-toluenesulfonic acid (p-TSA) as a catalyst under two conditions: organic solvent and solvent-free media. The present procedure offers several advantages, such as