The best results of the waste 1,1,2-trichloroethane dehydrochlorination by 10 wt % NaOH are obtained in temperature 70-80 degrees C at NaOH/112-TCE molar ratio 1.1:1 and flow rate 270 g/(dm(3) h). In these conditions 98.3 wt % vinylidene chloride and aqueous layer (13 wt% NaCl + 0.07 wt% NaOH) are obtained. Vinylidene chloride yield is 97.5 mol %.