Partition coefficients between 1-octanol and water, Kow, of 16 C-7 cyclic hydrocarbons were measured using the classic shake-flask method or the more recent slow-stir method. For eight compounds, both methods were used and the results are summarized by log Kow(shake flask) = m log Kow(slow stir), where m is 0.998 ± 0.003 (±SD). The compounds include quadricyclane, bicyclohepta-2,5-diene, norbornylene, norborane, and commercially available derivatives containing oxygen or halogen atoms. The rapid hydrolysis of three halogenated derivatives prevented direct measurements; estimates for these were calculated from retention times measured with a C-18 reverse-phase column. The compounds are hydrophilic to moderately hydrophobic; the values of log Kow range from -0.42 to 3.78.