This study was conducted to quantify heat and moisture production (HMP) of W-36 laying hens in their prime laying phase (27 to 33 weeks of age) using four large-scale indirect animal calorimeters. Two experiments were conducted involving two groups of hens. The hens were exposed to conditions of 24°C to 27°C and concomitant relative humidity (RH) of 45% to 65% for six weeks. In each experiment, a total of 216 laying hens were used, with 54 hens housed in each of the four calorimeters at the cage stocking density of 435 cm2 hen-1 (67 in.2 hen-1) that was typical of industry practice. Total heat production (THP), room-level latent heat production (LHP), and room-level sensible heat production (SHP) were expressed as daily time-weighted average (TWA), with an average of 16 h light and 8 h dark. The results showed that HMP was similar for the 24°C to 27°C temperature range. THP, LHP, and SHP, in W kg-1 (mean ±SE) were, respectively, 6.1 ±0.3, 2.3 ±0.2, and 3.8 ±0.1 for the daily TWA; 6.5 ±0.3, 2.4 ±0.2, and 4.1 ±0.1 for the light period; and 5.4 ±0.3, 2.2 ±0.2, and 3.2 ±0.1 for the dark period. The HMP data contribute to the design and operation of ventilation systems in modern laying hen housing.