Detailed Nusselt number distributions are presented for a two-pass square channel with one ribbed wall. This wall of the channel is sprayed with thermochromic liquid crystals, and a transient test is run to obtain the local beat transfer coeffcients. Results are presented for Reynolds numbers ranging from 6000 to 60 000. The rib height-to-hydraulic diameter ratio is 0.125; the rib pitch-to-height ratio is 10; and the rib configurations are 90 degrees parallel, 60 degrees parallel, 60 degrees V, and 60 degrees broken V. Detailed measurements are presented in the first pass, before the 180 degrees turn, in the turn region, after the turn, and further downstream in the second pass. The detailed distributions provide a clear understanding of the secondary flows induced by the 180 degrees turn and the rib turbulators.