Iodine-piperazine or chloranil-piperazine charge-transfer complexes have been used for the sensitive assay of piperazine or its salts; these complexes exhibit intense absorption bands in the electronic spectrum. The molecular ratios of the reactants in the complexes have been established and the experimental conditions leading to maximum charge-transfer bands were also studied. The proposed procedures have been applied successfully to pure samples and drug formulations with good accuracy. The average recovery was 100.26–100.84% with piperazine-iodine and 99.33–100.33% with piperazine-chloranil charge-transfer complexes, with an average standard deviation for each method of 0.8–3.9%.