Networks of polybutadiene were synthesized by reaction in solution with 1,6-hexane-bis-1,2,4-triazoline-3,5-dione. Polybutadienes of narrow molecular weight distribution were used. The kinetics of the crosslinking were studied in the visible region of the spectrum. Viscometric measurements allowed determination of the gel point as a function of the concentration of crosslinking agent. The results were interpreted in terms of the Flory-Stockmayer theory of gelation. A high proportion of loops was formed.