The compositional versatility of I 2 –II–IV–VI 4 tetrahedrally-coordinated compounds allows for accommodating their functional properties to numerous technological applications. Among them, Cu2 ZnSnSe4 is an emerging photovol-taic material and Cu2CdSnSe4 displays excellent thermoelectric properties. The third compound of this family, Cu2HgSnSe4 , remains relatively unexplored. Herein, a synthetic route to produce Cu2HgSnSe4 nanoparticles with narrow size distribution and controlled composition is presented. Cu2HgSnSe4 nanoparticles were subsequently used as building blocks to produce bulk nanocrystalline materials, whose thermoelectric properties were analyzed. A very preliminary adjustment of the material composition yielded Seebeck coefficients up to 160 μV K−1 , electrical conductivities close to 10^4 Sm−1 and thermal conductivities down to 0.5 Wm−1K−1 .