A commercially available wood-based granular activated carbon (WHK) and a weak acid fibrous ion exchanger (K-4) were evaluated for the removal of mercury and cadmium from aqueous solution. As-received granular WHK was modified electrochemically to enhance cation sorption capacity for comparison with K-4. Granular carbon samples were characterized by direct titration, X-ray photoelectron spectroscopy (XPS), elemental analysis, surface area, electrophoretic mobility measurements, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The sodium sorption capacity of K-4 was 4.28 mmol g(-1) compared to 1.27 mmol g(-1) for as-received WHK. Electrochemical oxidation for 3 h increased the ion exchange capacity of WHK to 2.57 mmol g(-1). Elemental analysis and XPS showed a noticeable increase in the oxygen content of electrochemically modified WHK, which was reflected in a higher content of acidic oxygen-containing groups and a shift of the isoelectric point to lower pH values compared to as-received WHK, Batch sorption experiments showed that K-4 is more effective for the removal of cadmium than mercury when compared to modified WHK. The effect of pH on sorption isotherms indicated that metal uptake increased with increasing pH. Small-scale studies indicated that breakthrough occurred at 20 and 75 bed volumes for mercury and cadmium respectively when a 1 nM mixed cadmium and mercury feed solution at pH 6 was passed through a column packed with modified WHK. This indicated that modified WHK is more selective for cadmium than for mercury.