  We show that the previously unreported ternary $\sigma$-phase material
Nb$_{20.4}$Ru$_{5.7}$Ge$_{3.9}$ is a superconductor with a critical temperature
of 2.2 K. Temperature-dependent magnetic susceptibility, resistance, and
specific heat measurements were used to characterize the superconducting
transition. The Sommerfeld constant $\gamma$ for
Nb$_{20.4}$Ru$_{5.7}$Ge$_{3.9}$ is 91 mJ mol-f.u.$^{-1}$K$^{-2}$ and the
specific heat anomaly at the superconducting transition,
$\Delta$C/$\gamma$T$_c$, is approximately 1.38. The zero-temperature upper
critical field ($\mu_0$H$_{c2}$(0)) was estimated to be 2 T by resistance data.
Field-dependent magnetization data analysis estimated $\mu_0$H$_{c1}$(0) to be
5.5 mT. Thus, the characterization shows Nb$_{20.4}$Ru$_{5.7}$Ge$_{3.9}$ to be
a type II BCS superconductor. This material appears to be the first reported
ternary phase in the Nb-Ru-Ge system, and the fact that there are no previously
reported binary Nb-Ru, Nb-Ge, or Ru-Ge $\sigma$-phases shows that all three
elements are necessary to stabilize the material. A $\sigma$-phase in the
Ta-Ru-Ge system was synthesized but did not display superconductivity above 1.7
K, which suggests that electron count cannot govern the superconductivity
observed. Preliminary characterization of a possible superconducting
$\sigma$-phase in the Nb-Ru-Ga system is also reported.
