Experimental results for the convective heat transfer and flow friction characteristics of plate-fin type heat transfer surfaces are presented for five surfaces. Four surfaces had a sinusoidal fin geometry. Two of these were fabricated of stainless steel, two of nickel. One of the nickel surfaces had perforated nickel fins. The fifth surface was fabricated of stainless steel and had a triangular fin geometry. The heat transfer data were obtained by the single-blow transient testing technique and by the cyclic testing technique. The two techniques compliment each other in extending the range of testing capability.