A new method for the fast direct chromatographic determination of strontium in seawater has been developed. Two coupled silica monolithic columns (total dimensions 200x4.6 mm I.D) chemically modified with iminodiacetic acid (IDA) functional groups were used for baseline separation of all alkaline-earth metals in seawater in less than 4 min at flow rate of 4.0 mL min(-1), using an eluent containing 0.25 M sodium chloride and 2 mM glycolic acid, pH 5.11. Several colour-forming ligands, including o-cresolphthalein complexone (o-CPC), methylthymol blue (MTB), xylenol orange (XO), 4-(2-pyridylazo)resorcinol (PAR) and ZnEDTA-PAR were evaluated as reagents for post-column reaction (PCR) based spectrophotometric detection. Sensitivity of the developed method for strontium was at the low mg L-1 level in undiluted seawater samples, in the presence of excessive amounts of calcium and magnesium, using post-column reaction detection with o-CPC at 570 nm. The method allowed quantitative determination of strontium in seawater samples (LOD 3.23 +/- 0.15 mg L-1, s(r)= 4.6%), with direct injection of just 4 mu L of seawater onto the chromatographic column.