Reductometric determinations of five azo pigments are reported. Direct potentiometric titration was performed on a solution of the pigment in acetonitrile/methanol with titanous chloride to the inflection potential pre-determined by manual titration. Standard deviations ranged from 0.5 to 0.25 percent for seven determinations of each pigment (97.8 percent or over). Optimal conditions for the determination were found from investigations involving direct and indirect titrations with Cu(II) and Ti(III) in various media. -- AATA