Herein, we describe the synthesis of 4, 5-disubstituted-3-trihalomethylisothiazoles from trihaloacetonitriles and 2-cyanothioacetamides or 2-ethoxycarbonylthioacetamides. The reactivity of the necessary trihaloacetonitriles has a significant impact on the observed reaction pathways. Reactions with CF3CN require an oxidant to mediate cyclization, while CCl3CN functions as both the reactant and oxidant.