In this work, the effects of boroaluminizing thermochemical treatments in solid medium on the microstructure and the surface properties of XC38 steel have been studied. The obtained layers have been characterized using optical and scanning electron microscopy, X-ray diffraction and Vickers microhardness. The comparative study of boroaluminized layers obtained by simultaneous and consecutive processing steps of treatment show that the much thicker diffusion layer (with 114 mu m) is obtained after a boriding followed by aluminizing treatment with a significant improvement of microhardness value which reach 1020 HV.