  Two novel of boron-rich selenides, orthorhombic B$_6$Se and rhombohedral
B$_{12}$Se, have been recently synthesized at high pressure - high temperature
conditions. Room-temperature compressibilities of these phases were studied in
a diamond anvil cell using synchrotron powder X-ray diffraction. A fit of
experimental p-V data by third-order Birch-Murnaghan equation of state yielded
the bulk moduli of 155(2) GPa for B$_{12}$Se and 144(3) GPa for B$_6$Se. No
pressure-induced phase transitions have been observed in the studied pressure
range, i.e., up to 35 GPa.
