Sinusoidal short-channel structures, as developed by Kolodziej and Lojewska, 2007, were made of Kanthal steel sheets and studied for heat transfer efficiency under laminar air flow in a lab. unit. The results were presented as dimensionless functions of Fanning coef, Re and Nu nos. vs. dimensionless length of the channel. Per analogy, the mass transfer efficiency in the structures was also estd. The studied structures were more efficient than wire grids (61.7 mesh/in), grain beds (2 mm) and ceramic monoliths (100 channels/in(2)).