A mercury-free thick-film graphite-containing electrode modified with formazan is proposed for determining manganese(II) by cathodic stripping voltammetry. The detection limit for manganese(II) found with this electrode is 0.04 mug/L at a preconcentration time of 60 s. The analytical signal from manganese(II) is a linear function of its concentration in the range 0.1 to 30 mug/L. The results of determining manganese in natural and drinking waters are presented.