  We show that the superhard boride WB$_{4.2}$ is a superconductor with a T$_c$
of 2.05(5) K. Temperature-dependent magnetic susceptibility, electrical
resistivity, and specific heat measurements were used to characterize the
superconducting transition. The Sommerfeld constant {\gamma} for WB$_{4.2}$ is
2.07(3) mJ mol$^{-1}$ K$^{-2}$ and the {\Delta}C/{\gamma}T$_c$ = 1.56, which is
somewhat higher than what is expected for weakly coupled BCS type
superconductors. The H$_{c2}$ vs T plot is linear over a wide temperature range
but does show signs of flattening by the lowest temperatures studied and
therefore the zero-temperature upper critical field ({\mu}$_0$H$_{c2}$(0)) for
WB$_{4.2}$ lies somewhere between the linear extrapolation of
{\mu}$_0$H$_{c2}$(T) to 0 K and expectations based on the WHH model.
