The role of the soil organic matter (SOM) and clay minerals in pentachlorophenol (PCP) sorption-desorption was studied with two bulk soils, two modified soils, two artificial soils and two pure clays. All sorption isotherms were convex down and fit to Freundlich equation. Desorption isotherms showed an open loop hysteresis. Increasing the initial PCP concentration increased the sorbed amount, which enable more PCP to be desorbed during the desorption process. Analysis of the modified soils and artificial soils experiments showed that the type and quantity of clay minerals was the dominant factor on sorption and desorption of PCP. This conclusion was corroborated by the pure clays experiments. Two pure strains and their mixed culture were used for PCP biodegradation in CO and NM bulk soils. Analysis via statistical methods showed that the bacteria had different degradation efficiencies on PCP degradation in each soil. First, all bacteria resulted in a higher PCP degradation when presented in NM soil. Second, Flavobacterium sp. degraded more PCP than Arthrobacter sp. in CO soil, and lower when in NM soil. The mixed culture achieved the highest degradation efficiency in both soils.