A highly sensitive and simple method for the determination of germanium(IV) has been developed. Germanium(IV) was extracted on a membrane filter as the phenylfluorone complex from a dilute hydrochloric acid (1 + 7) medium containing Zephiramine and the complex on the membrane filter was then determined by solid-phase spectrophotometry. A 1000-fold molar excess of Zephiramine over germanium(IV) at the nmol level was required for the formation of the germanium(IV)-phenylfluorone complex. The detection limit of germanium(IV) was found to be 1.9 ng for 40 ml of the sample solution. The method was applied to the determination of germanium(IV) in hot spring water and groundwater. The concentrations of germanium(IV) found were in the range 4.36–37.7 p.p.b. for hot spring water and 0–1.97 p.p.b. for groundwater.