A chamotte rod is transformed in vapors through chemical reactions, at temperatures exceeding 5000 K. SiO2 micro-tubes formation is determined by a low vapor concentration and a stable vapor flow, along the streamlines of the plasma jet, and, respectively, by the difusion processes, in non-stationary regime, inside the liquid membrane. A mass of SiO2 vapor, in the range of 0.5 x 10(-8) kg-10 x 10(-8) kg, allows one to obtain micro-tubes with the outer diameter between 6.2 and 28.8 mum and the inner diameter between 3.8 and 12.2 mum.