The portable high precision small/wide angle X-ray scattering diffractometer (modified Bonze-Hart optical scheme) was designed and developed for the investigation of structure rearrangement during liquid state-solid state transformations (with reaction time of 10 h or more) for the investigation of the process of solid state phase formation. The FEM detectors are used as monitor and detector. The double crystal Si 111 analyzer (with changeable relative angle of the second crystal) is used as analyzer. All controlling electronics are designed in CAMAC. The diffractometer is controlled by a Sun SPARCStation with SVIC/VCC modules under a Solaris 2.4 operating system, and allows one to obtain the SAXS curves with accuracies (on s-vector for photon energy 8 keV) of about δs∼0.002 nm -1, smin∼0.005 nm -1 (scattering centers with the size of about 200-500 nm may be observed) and smax∼50 nm -1 (scattering angle is about 80°).