  We report both experimental and theoretical investigations of the physical
properties of Ba$_\mathrm{2}$Mn$_\mathrm{2}$Sb$_\mathrm{2}$O single crystals.
This material exhibits a hexagonal structure with lattice constants: a =
4.7029(15) \AA{} and c = 19.9401(27) \AA{}, as obtained from powder X-ray
diffraction measurements, and in agreement with structural optimization through
density functional theory (DFT) calculations. The magnetic susceptibility and
specific heat show anomalies at T$_\mathrm{N}$ = 60 K, consistent with
antiferromagnetic ordering. However, the magnitude of T$_\mathrm{N}$ is
significantly smaller than the Curie-Weiss temperature
($\mid$$\mathrm{\Theta_{CW}}$$\mid$ $\approx$ 560 K), suggesting a magnetic
system of reduced dimensionality. The temperature dependence of both the
in-plane and out-of-plane resistivity changes from an activated at $T$ $>$
T$_\mathrm{x}$ $\sim$ 200 K to a logarithmic at $T$ $<$ T$_\mathrm{x}$.
Correspondingly, the magnetic susceptibility displays a bump at T$_\mathrm{x}$.
DFT calculations at the DFT + U level support the experimental observation of
an antiferromagnetic ground state.
