Experimental results are reported for perforated-plate heat transfer matrices. Friction and heat transfer data were obtained for low-Reynolds-number continuum flow (R(d) less than or similar to 100) over a range of geometric parameters, including plate open-area ratio, plate spacing-to-thickness ratio, and hole diameter-to-plate thickness ratio. Friction factors were obtained from isothermal pressure drop tests) and single-blow transient tests were used to obtain heat transfer coefficients. The main trends in the data are identified. A modified London area goodness factor is introduced to account properly for the effect of plate open-area ratio on thermal-hydraulic performance. Implications of the results for heat exchanger design are discussed briefly.