We have observed a superconducting transition at 12 K in the system Y-
Ni-B (nominal composition: YNi4B). Sharp drop in resistivity (it does
not go to zero) and a diamagnetic susceptibility below 12 K clearly in
dicate a superconducting transition. Possibility of a magnetic phase t
ransition at this temperature is ruled out by our specific heat measur
ements. Superconducting fraction of our samples, as estimated from Mei
ssner effect measurements, is about 2%.