Charcoal results from the incomplete burning of plant material and it is found in most surface horizons of soils, but little is known about how it affects soil properties. The objectives of this study were (1) to determine the chemical and physical properties of ponderosa pine charcoal produced under controlled conditions, (2) to compare the properties of the laboratory-produced charcoal to those of wildfire-produced charcoal after it had resided in the soil for a number of years, and (3) to determine how charcoal additions to soil material affect water-holding capacity and soil color. We worked with ponderosa pine because it is common in the western United States and is a dominant species in an ecosystem that burns naturally. We found that ponderosa pine charcoal has a CEC on the order of 20-30 cmol kg-1 and accumulates native cations on its exchange sites when it is in the soil. Samples of laboratory-produced and field-collected charcoal were very water repellent (water drop penetration time >2 h), except samples collected immediately below the litter layer, which were much less repellent (water drop penetration time <10 s). The charcoal C/N ratios were very large, and the laboratory-produced charcoal ratio (644) was about three times larger than the field-collected charcoal ratio (196-263). Addition of finely divided charcoal to mineral soil significantly increases the available water capacity and darkens the soil. Charcoal is not simply an inert compound in soils. It may play an important role in determining the properties and behavior of some surface soil horizons.