Influence of reagent ratio on the composition of products of the reaction between 1,1,2,2-tetrabromoethane and imidazole or 1,2,4-triazole in a superbasic medium (potassium hydroxide – dimethyl sulfoxide) was investigated using GC/MS technique. It was found that nucleophilic substitution reaction is always accompanied by elimination reactions (dehydrobromation and debromation). In addition to 1,1,2,2-tetra(azol-1-yl)ethane, 1,1,2-tri(azol-1-yl)ethenes and 1,2-di(azol-1-yl)ethenes, as well as 1,2-di(azol-1-yl)-1-bromoethenes were detected. Reaction pathway that explains the formation of all major products was proposed.