Cobalt is widely used in different industrial processes for production of various synthetic materials. For assessment of human exposure to toxic metal of Co (II), environmental and biological monitoring are essential processes, in which, preparation of samples is one of the most time-consuming and error-prone aspects prior to instrumental analysis. The aim of this study was to achieve optimum factors necessary for development of a sample preparation technique for cobalt (II), present in urine, hair, and nail samples followed by ATOMIC ABSORPTION spectrometry. Solid phase extraction (SPE) using mini columns filled with Chromosorb 102 resin was optimized regarding sample pH, ligand concentration, loading flow rate, elution solvent, sample volume (up to 500 ml), elution volume, amount of resins, and sample matrix interferences. Cobalt ion was retained on sorbent and was eluted with 2 M HNO3 followed by determination by flame ATOMIC ABSORPTION spectrometry. Obtained recoveries of cobalt ion were more than 92%. To evaluate occupational exposure to Co (II), successful applicability of the optimized method for human exposure was used by treatment real samples, including urine, hair, and nail. Suitable results were obtained for relative standard deviation (less than 10%). This optimized method can be considered successful in simplifying sample preparation for trace residue analysis of Co (II) in different matrices when an evaluation of occupational and environmental exposures is required.