Hole trap distribution and time dependence of the charge-free layer in the gate-oxide of p-channel metal oxide semiconductor (pMOS) transistors have been investigated after uniform hot-hole injection into the oxide of a set of pMOS transistors having very thin oxide thicknesses in the range of 4.6 to 10.6 nm. It has been found that the trap distribution has an exponential variation with respect to the distance from the Si/SiO2 interface and exists within 6 nm from the interface. A slight dependence of trapped-hole density on the oxide electric field was also found. A charge-free layer exists near the interface as a consequence of hole detrapping during relaxation. Measured time dependence of the charge-free layer during relaxation reveals that it increases initially with time and saturates at around 4 nm.