We have studied the influence of thermal treatment and aging on electrical transport in porous Si. The conductivity is found to decrease for annealing temperatures up to 400 degrees C. For a process temperature of 600 degrees C the conductivity reaches a maximum. Above this a continuous reduction in the conductivity is observed with rising annealing temperature. It has been found that aging affects the conductivity depending on storage in dry or humid ambient. Fourier transform IR spectra are used to correlate the changes in conductivity to different chemical compositions of the porous Si internal surface.