The 2-ethenylfuran polymerization catalyzed by trifluoroacetic acid in a water-chloroform mixture yields oligomers at the beginning and products at higher reaction times. Some features of the polymerization resemble a polycondensation process such as molecular weight increasing with time. Polymers obtained were characterized and its structure did not differ from those obtained with 1 (2-furyl) 1-ethanol. Thus, a vinylic propagation can be ruled out. However, the monomer concentration decreased steadily during polymerization and the kinetic first order in monomer and catalyst could only be explained assuming a steady state for the polarized ester concentration, which is the active center that gives the corresponding carbinol. Both of these facts suggest a chain reaction. Computer simulation helped to confirm the envisaged mechanism for this system.