There are three mathematical models for calculating the electric charge acquired by particles of the k-phase in the ionized flow of combustion products of model liquid rocket engine (LRE) on fuel: ethyl alcohol (75% by volume) and gaseous oxygen with the following operating parameters in the paper. The oxidizer excess ratio is taken from the range α = 0.6…1.5, and the pressure in the combustion chamber pc = 0.6…3.0 MPa. Particles of metal and metal oxide are considered. These particles may appear in the tract of liquid-propellant rocket engine during its anomalous operation (destruction). As a result of calculations according to these models, the values of electric charges for the radius range of particles of the condensed phase 1…60 microns were obtained. It was estimated the area of model application under consideration with variation of the boundary conditions in relation to the operating modes of the model LRE. Obtained results may be used during parametric diagnostics of technical condition of the rocket engine.