3-nitropropene 1

2-epoxide was successfully polymerized and eopolymerized with tetrahydrofuran in the presence of boron trifluoride etherate-butanediol (1

4) as a catalyst system to yield polyethers containing terminal hydroxy groups and nitrome-thyl groups in side chain. The viscous oily prepolymers can be satisfactorily crosslin-ked with toluene diisocyanate and glycerine to form rubbery elastomers. Some characteristic properties of the prepolymers and crosslinked polymers have been studied.