  We have performed low-temperature specific heat and thermal conductivity
measurements of the Ni-based superconductor BaNi$_2$As$_2$ ($T_\mathrm{c}$ =
0.7 K) in magnetic field. In zero field, thermal conductivity shows $T$-linear
behavior in the normal state and exhibits a BCS-like exponential decrease below
$T_\mathrm{c}$. The field dependence of the residual thermal conductivity
extrapolated to zero temperature is indicative of a fully gapped
superconductor. This conclusion is supported by the analysis of the specific
heat data, which are well fit by the BCS temperature dependence from
$T_\mathrm{c}$ down to the lowest temperature of 0.1 K.
