This study investigated the different forms and availability of P in soil profiles from temperate forests in southern Chile (two sites: Nothofagus obliqua (Mirb.) Bl. and Nothofagus betuloides (Mirb.) Oerst.) and Flanders, Belgium (two sites: Pinus nigra Arnold and Betula pendula Roth). Soils were sampled according to genetic horizonation and analysed for organic matter, oxalate-extractable P, Al and Fe, total inorganic P and total organic P. Phosphorus availability was assessed using an isotopic exchange technique and anion exchange membranes. The total P content was higher for the Chilean andosols and remained relatively high in the whole soil profile (1413-187 mg P kg-1) whereas total P decreased sharply in the lower horizons of the Flemish podzols (575-4 mg P kg-1). There was a strong predominance of organic P in the Chilean soils (up to 90% of total P). The high volcanic activity in Chile is responsible for the large amounts of allophone, which entail high P-fixing capacities in these soils. Notwithstanding the much larger total P content in Chilean andosols compared to the Flemish podzols, both soil types feature comparable amounts of available P (AEM-P). The two phosphorus availability indices (IEP and AEM-P) correlated rather well for the Flemish forest sites (R² = 0.67), while the same correlation was lacking for the Chilean soil profiles (R² = 0.11). However, a strong relation between AEM-P and the organic matter content of the andosols emerged. The presence of Al and DOC in the AEM-extracts of eight selected Chilean soil samples suggests the extraction of organo-mineral colloids by the membrane. The lack of correlation between AEM-P and IEP for the Chilean soils may be related to the presence of these colloids, as they may lead to an overestimation of IEP as well as biased AEM-P values. Differences in forms and availability of phosphorus between the Chilean and the Flemish soil profiles were mostly ascribed to differences in soil properties rather than to differences in anthropogenic influences