The partition coefficient (K_x) of ω-phenylalkanol (C₆H₅(CH₂)m_pOH, m_p = 0 - 6) between water and micelles of a synthetic surfactant, sodium perfluorooctanoate (SPFO) and a biological surfactant, sodium taurodeoxycholate (NaTDC) has been determined by a differential spectroscopic method at 25°C. The linear dependence of the standard free energy change of transfer calculated from K_x on the alkyl chain length of the alkanols (m_p≥ 4) yields the standard free energy change (ΔG°(CH₂)) per methylene group from water to micelles. ΔG°(CH₂) values for SPFO -, and NaTDC - ω-phenylalkanol systems are -1.68 and -2.50 kJ mol^-1, respectively.