Abstract: A flow injection system, incorporating a flow-through four-electrode cell for controlled-potential conductance measurements, is described. For the analysis, a sample (35 µL) of pure centrifuged fruit juice was injected into the carrier stream (flow rate 20 mL min-1), and the mixing-coil length was 100 cm. There was good correlation (r = 0.992) between peak conductance and acid content (as shown by addition of malic and citric acids to the juice). By this method, 50 samples could be analyzed in 1 h, and the coefficient of variation of the results for any given juice was 0.5% (n = 20). To reduce the viscosity of the juice, dilution (1:3 or 1:4) before injection is recommended.