In this study, inorganic mercury [iHg (Hg2+)] and monomethylmercury [MeHg (CH3Hg+)] ions have been preconcentrated and determined by a column solid phase extraction method. Cold vapor atomic absorption spectrometry was used for the determination of mercury species. Optimum retention and elution parameters were determined for both mercury species separately. For this purpose, the effect of pH, flow rate and volume of sample solution, type, and concentration of eluent on the recovery of mercury species were investigated. Effects of possible interfering ions were also studied. Optimum values of flow rate, pH, and volume of sample solution were found to be 3mL min1, 4.0 and 50mL, respectively, for both iHg and MeHg ions. Although the both species were retained at pH 4, the elution could be performed only with different eluents. While MeHg ions were eluted with 10mL of 0.1mol/L HCl solution, iHg ions were eluted with 10mL of 0.2molL1 thioureasolution in 3molL1HCl. Limits of detection for iHg and MeHg were 0.44 mu gL1 and 0.56 mu gL1, respectively. To validate the proposed speciation and/or preconcentration method, a certified reference material (ERM-CE464) was analyzed and MeHg was determined with a relative error of 7.3%. The accuracy was also checked by analyzing spiked water and fish samples for both species.