We have studied (LuC)2(Ni2B2) and (LuC)(Ni2B2) at ambient and high pre
ssures. Superconductivity was discovered in (LuC)2(Ni2B2) at 2.9 K. Pr
essure was found to suppress both the electrical resistivity and the s
uperconducting transition temperature rapidly for (LuC)2(Ni2B2) but on
ly slightly for (LuC)(Ni2B2), in spite of their similar chemical-bondi
ng behavior. The observations can be understood in terms of the smalle
r density of states at the Fermi surface and the greater pressure-indu
ced band broadening of (LuC)2(Ni2B2) than (LuC)(Ni2B2).