Tenser LEED has been used to determine the geometry of a p(3 x 1) phase formed by benzene adsorption to saturation coverage on Co(10 (1) over bar0) at 300 K. In contrast to benzene overlayers previously subjected to quantitative surface structural analysis, adsorption occurs with the ring in a tilted geometry across the substrate close packed [12 (1) over bar0] atomic rows in an off-centre bridge site with C, symmetry.