•This study investigated B doping of multi-walled CNTs (MWCNTs) and its effect on field emission properties.

•We synthesized doped MWCNTs using electric arc discharge where B dopants were introduced from anode electrodes. Crystallinity and thermal stability of doped MWCNTs have been evaluated using Raman spectroscopy and thermogravimetric analysis, respectively.

•Upon B doping, crystallinity was degraded but oxidation resistance was improved as compared to pristine MWCNTs.

•Diameters of MWCNTs were reduced by B doping. Doped MWCNTs showed better turn-on electric fields and higher field enhancement factor as compared to pristine MWCNTs.

•These doped CNTs seem to be promising for field emitter materials of x-ray tubes and UV-lamps.