The critical current densitiesJcof Chevrel phase wires with niobium as an antidiffusion barrier were measured in magnetic fields up to 24 T. At 20 T and 1.9 K,Jcreaches5.4×108A/m2and decreases slightly down to3.1×108A/m2at 24 T. A wire with a 20&percent; superconducting cross section has been successfully drawn and its overall critical current densityJcovexceeds 100A/mm2at 1.9 K up to a magnetic field slightly above 20 T. This demonstrates the ability of Chevrel phase wires to be used in high magnetic field applications. Moreover, some parts of the coil have certainly higherJc,sinceJcis very often limited by a thermal excursion of the entire coil. The effective upper critical field&mgr;0Hc2*,deduced from the magnetic field dependence ofJc,is too low compared to the expected bulk value, indicating that superconducting properties at the grain boundaries are still degraded. If the bulk&mgr;0Hc2can be restored at the grain surfaces,Jcovshould be higher than 100A/mm2up to at least 30 T. ©1997 American Institute of Physics.