Radiata pine bark was extracted using hot compressed water with or without 1 % NaOH at temperatures of 100 °C and higher under different pressures for various holding times. The yields of extractives and polyflavanoids obtained from the extraction of the bark using hot compressed water without NaOH were much lower than those from conventional extraction at ambient pressure. This result has confirmed our previous experience. However, when 1 % NaOH (based on the weight of the oven-dried bark) was added to the compressed water system, the yields of the extractives and polyflavanoids increased remarkably, and the highest yield (31.3%) of the extractives was obtained at a peak temperature of 140°C and a pressure of lOatm followed by immediate cooling. Furthermore, the bark particle size and the ratio of bark to solvent affected to a much lesser extent the yield of the extractives in this new method, compared with that in the conventional method. The solubility behaviour of the tannin extracts in the hot compressed water is discussed in relation to the extractives yield from the extraction of the bark at temperatures higher than 100°C and at pressures higher than ambient.