In the present study, a green and simple technique has been used for the preconcentration , flotation and spectrophotometric detection of Co (II) in pharmaceutical and water samples is established. At pH 4, the chromogenic reagent 4-(2pyridyl azo) resorcinol (NaPAR) reacts with Co(II) to form a pink 1:2 (M:L) complex in aqueous solution. This complex has been successfully separated by flotation by the aid of the anionic surfactant, oleic acid(HOL). The concentration of Co(II) in the scum layer was determined easily by spectrophotometry at 510 nm. The parameters that influence the flotation and spectrophotometric determination of Co (II) were studied. Beer's law was obeyed over a concentration range 0.01-0.32 µg ml-1 in the aqueous as well as in the scum layer. The molar absorptivity of the Co(II)-NaPAR in the aqueous and scum layer were found to be 1.2×104 L mol-1 cm-1and 1.54×105 L mol-1 cm-1, respectively. The detection limit of the proposed technique, the recovery % (R%) and the relative standard deviation(RSD%) are 3.09 ng ml-1, 98 % and 1.5%, respectively. The method was verified by analysis of real certified samples. The proposed procedure was applied to determine Co (II) in water, pharmaceutical samples as well as in synthetic mixtures. The mechanism of flotation is proposed.