Particle image velocimetry (PIV) is used to study the turbulent flow over the ribroughened wall of a cooling channel model in rotation. The aspect ratio is 0.9, the blockage ratio is 0.1 and the rib pitch-to-height ratio is 10. The flow direction is outward, with a Reynolds number of 1.5.104 and a rotation number of 0.3 in both rotational direction. The PIV system rotates with the channel, allowing to measure directly the relative flow velocity with high spatial and temporal resolution. Coriolis forces affect the stability of the shear layers: clockwise (counter-clockwise) rotation inhibits (enhances) the turbulent motion, influencing velocity, vorticity and turbulence intensity of the flow. The time-resolved measurements show the effect of rotation on the shear layer instability and on the consequent formation of spanwise vortices, as well as on the time trace of the reattachment point. Turbulent energy spectra suggest that all temporal scales are affected by rotation.