We evaluate the possibility of using surface tension as the main information parameter for determining the order of the polycondensation reaction in the main reagent occurring in the “glyoxal-bark”. Surface tension was calculated according to the method of Owens, Wendt, Rabel and Kaelble (OWRK). In addition, the identified minus the first order of the polycondensation reaction may be due to the fact that the limiting stage occurs in the diffusion region. In this case, blocking the free reactive surface centers of the plant component of the mixture by products of the primary interaction leads to a slowdown of the process, despite an increase in the concentration of glyoxal. The unit modulus of the reaction order means that one molecule of glyoxal is involved in an elementary act of interaction of glyoxal with the structural units of the lignin macromolecule. This confirms both the working hypothesis on the mechanism of structure formation in “glyoxal-bark” system, and the possibility of using surface tension for the kinetic description of heterogeneous processes.