To understand friction under refining conditions, measurements of sliding friction between wood and steel were made in a steam environment. To achieve different testing temperatures (100-170ºC) the steam pressure was set to various levels. Two wood species, Norway spruce and Radiata pine, were examined in this study. The friction coefficients of native wood increased with temperature up to a critical point where fibers started to wear off from the surface. This point was observed at a lower temperature for Radiata pine than for Norway spruce. After extracting the samples with acetone and dichloromethane, friction-augmenting effects were observed and local friction maxima appeared for both spruce and pine around 125ºC. It is suggested that this local maxima is due to energy dissipative processes and related to the softening temperature of lignin. Experiments with sulfonated samples of Norway spruce supported this suggestion.