This paper reports a new and simple microextraction procedure for cobalt determination using green ionic hydrophobic deep eutectic solvent in developing air-assisted liquid-phase microextraction and flame atomic absorption spectrometry. The complexation of Co(II) ions was carried out by using dithizone solution as complexing agent at pH 5. The key variables affecting microextraction steps were optimized by response surface methodology (RSM) based on central composite design. Under the optimum microextraction conditions, calibration graph was linear in the range of 0.1-500 mu g L-1 Co(II) with correlation coefficient of 0.9985. Additionally, detection limit, quantitation limit and enrichment factor were found to be 0.04 mu g L-1, 0.1 mu g L-1 and 175, respectively. The reproducibility and repeatability were <= 2.9% and <= 3.6%, respectively. Based on the results obtained, the proposed methodology has been successfully employed for Co analysis in liquid and solid samples with recovery range of 94.2-105%.