Abstract: A RuO2-modified carbon paste electrode (prep. described) was used in the constant-potential cyclic voltammetric flow detection of carbohydrates. Samples in 1 M NaOH were analyzed at the electrode (+0.4 V; 20 mV s-1) with Ag - AgCl and Pt-wire reference and auxillary electrodes, respectively. The effects of variables, viz, pH, flow rate, operating potential and surface 'loading', were studied. The method was applied in the detection of deoxyribose, fructose, galactose, gluconic acid, glucose, glycerol, lactose, maltose, ribose and sucrose (electrode responses are tabulated). Working ranges were from 0.1 to 10 mM glucose and 0.1 to 1 mM ribose, fructose and galactose. The detection limits were pmol-levels and the coefficient of variation (n = 72) was 1.2%. The electrode was stable for >48 h with a signal loss of 10% over this period.