Fibrous polymer materials formed by LDPE melt spraying with a gas flow during extrusion were exposed to thermally stimulated depolarization. The analysis of thermally stimulated current spectra and the sample charge state has shown that the fibers possess the spontaneous polarizing charge. IR-spectroscopy has proved the material production to be accompanied by vinylene, vinyl, transvinylene and other nonsaturated groups formation. The latters are, probably, behaving as neutral trapping centers during their interaction with charge carriers formed at melt dispersion by the compressed gas flow and its contact with metal parts of equipment. The kinetics of these processes can be monitored by regulating technological regimes of fibrous material formation. Intensified action on the polymer melt might rise the spontaneous polarizing charge whose density can reach 10(-10) to 10(-12) C/cm(2). Charge of the materials under study is rather stable. It does not fall below 40% upon a 160-days storage in humid atmosphere. It appears thus that the technique of fibrous material production by polymer melt spraying is an electret method.