Evaluate the influence of water activity [aw], temperature and pH on the radial growth and lag phase of Physisporinus vitreus (E-642), a basidiomycete used in the biotechnical process of bioincising. Radial growth was monitored for 20 days on MEA medium. Five levels of aw (0.998, 0.982, 0.955, 0.928, 0.892) were combined with three incubation temperatures (10, 15, 20 °C) and three pH (4, 5, 6). Data analyses showed a highly significant effect of aw and temperature (P<0.0001), and a significant effect of pH (P<0.05). The radial growth rate and lag phase of P. vitreus were very sensitive to aw reduction. Although P. vitreus was able to grow at the selected temperatures and pH values, the lag phase increased with decreasing aw, and growth was already inhibited at aw = 0.955. Optimal conditions for growth of P. vitreus were aw = 0.998, 20°C and pH 5. The response surface model provided reliable estimates of the three kinetic parameters and confirmed the greater dependence on aw than on temperature or pH under in vitro conditions. Low levels of aw can prevent growth of P. vitreus, so wood moisture content should be adjusted accordingly.