Samples of p-type porous GaAs was obtained by electrochemical anodization of (100) oriented p-type GaAs. The formation of porous structure has been confirmed by Raman spectroscopy and scanning electron microscopy investigations. The low-frequency Raman shift of the peaks conditioned by the main optical phonons was observed in the Raman spectra of the porous GaAs. Estimation of the size of nanocryslallites in porous GaAs both by Raman shift and scanning electron microscopy gives approximately the same values and was about 10-20 nm. Photoluminescence investigations of porous GaAs exhibit the presence of two infrared and one visible bands.