Novel conducting oligocatecholborane (OCOB) with electrical conductivity of 3.73 × 10

−2

S cm

−1

was successfully synthesized by low-potential electropolymerization of catecholborane (COB) in boron trifluoride diethyl etherate at 0.70 V versus Ag/AgCl. FT-IR and

1

H-NMR spectra

together with the computational results

proved that COB was polymerized through the coupling at C

(4)

and C

(5)

positions and the reactive B — H bond was stable during the electrochemical polymerization. The resulting product was main

ly composed of oligomers with short chain lengths by GPC and mass spectral results. The as-formed OCOB film showed good electrochemistry in monomer-free electrolytes with the electrochromic property from opaque blue to sap green. Fluorescence studies indicated that soluble OCOB can emit bright blue light under excitation of 365 nm UV light with the maximum emission at 396 nm and a fluorescence quantum yield of 0.21. The deposited OCOB also exhibited favorable thermal stability and smooth and compact morphology even at high magnifications.