The rotational velocity of neutrally buoyant particles was measured in a planar Couette flow. The flow cross section is rectangular with a 4-to-1 (200 mm/50 mm) aspect ratio. The mixtures consist of uniform polystyrene spheres and a glycerol–water solution of specific density 1.052. Four sphere sizes have been tested: 3, 4.76, 6.35, and 7.94 mm. Particle motion in turbulent flow was recorded with a high-speed SP-2000 motion analysis system. The characteristics of particle motion, including particle spin, were measured as a function of the distance from the wall, at three shear rates corresponding to Re=4.6, 6.8, and 9.2×104. It was found that the particle angular velocity normalized by shear rate is a function of the normalized distance to the moving and stationary walls. The flow conditions are defined with measurements on mean velocities, particle velocity fluctuations, kinetic energy, inertial stresses, and diffusion coefficients.