Properties of stored peat were studied at sites near Evansburg, Alberta, and on the lease of Syncrude Canada Ltd. at Mildred Lake, Alberta. Physical, chemical, and microbiological properties of stored materials were compared with those of fibric moss peat, mesic moss peat, and mesic fen peat samples from undisturbed sites. Environmentally induced changes in peat properties were simulated in' the laboratory by freeze-drying, air-drying, and thawing peat samples. Air-drying and, to a lesser extent, freeze drying, resulted in deterioration of physical properties and in reduction of microbial activity. The stored materials at Evansburg consisted entirely of peat whereas at Mildred Lake the materials were heterogeneous peat-mineral mixtures which were grouped as follows: group I, peat predominant; group II, sand predominant; group III, sand-clay mixture; and group IV, peat-sand mixture. Optimum temperatures for microbial activity in the storage piles occurred near the surface and decreased with depth while optimum moisture conditions occurred near the 50 cm depth. Frost penetration was not greater than 1 m in any of the piles. Storage piles consisting of peat-mineral mixtures which had been fertilized had a somewhat higher level of microbial activity and organic matter decomposition than undisturbed peat or stored, relatively pure peat. Properties of the stored materials which were highly correlated with each other were carbon, nitrogen, respiration rate, enzyme activity, cation exchange capacity, ash content, bulk density, pore volume, and water capacity. Relatively simple methods for the characterization of ash, carbon, and bulk density of stored materials were used.