A mass transfer measuring technique is used to visualize and determine the shellside local heat transfer coefficients at each tube in two representative baffle compartments of a shell-and-tube heat exchanger with disc-and-doughnut baffles. The fluid flow adjacent to the tube is analysed and the heat transfer in the zones of separated flow discussed. The shellside flow distribution is determined through the measurements pf the local pressure drop in the baffle-tube and baffle-shell clearances. Compared to the single-segmental baffle, the disc-and-doughnut baffles have a higher effectiveness of heat transfer to pressure drop. This investigation presents also per-tube and per-compartment averaged heat transfer coefficients.