An adequate knowledge about bioavailable soil P of highly weathered tropical acid soils is a pre-requisite to their sustainable management for food production. The objective of this study was to characterize the bioavailable soil P status of six highly weathered low activity clay (LAC) soils from SW Ghana by using an isotopic exchange method. The bioavailable P was characterized by three factors, i.e intensity, quantity, and capacity inferred from experimental parameters that describe the dynamics of soil phosphorus through isotope exchange of phosphate ions and represented by a functional model with five compartments in which the pools have been defined according to their mean exchange time with the phosphate in soil solution. The results indicated that all the LAC acid soils had very low P fertility status as reflected by the low P concentration in solution, Cp (