In the present work, a methyl acrylate resin (Chromosorb 105) was used for on-line solid phase extraction and determination of traces cobalt by flame atomic absorption spectrometry (FAAS). Cobalt is preconcentrated at pH 9 onto mini column at NH3 media. The elution step for retained cobalt is performed with a stream of I M HCl at 4.0 mL/min and cobalt displaced is introduced directly into the nebulizer of flame atomic absorption spectrometer. The effects of analytical parameters including pH, flow rates etc., were investigated. The proposed method was successfully applied to the determination of cobalt in tap water and table salt samples. A detection limit of 2.5 mug/L for preconcentration at 4.0 mL/min is obtained and an enrichment factor of 50 could be achieved. The recoveries of spike additions to tap water and table salt samples were greater than 95%. The relative standard deviations were also below 4%.