  We investigate the external hydrostatic pressure effect on the
superconducting transition temperature (Tc) of new layered superconductors
Bi4O4S3 and NdO0.5F0.5BiS2. Though the Tc is found to have moderate decrease
from 4.8 K to 4.3 K (dTconset/dP = -0.28 K/GPa) for Bi4O4S3 superconductor, the
same increases from 4.6 K to 5 K (dTconset/dP = 0.44 K/GPa) upto 1.31 GPa
followed by a sudden decrease from 5 K to 4.7 K upto 1.75 GPa for
NdO0.5F0.5BiS2 superconductor. The variation of Tc in these systems may be
correlated to increase or decrease of the charge carriers in the density of
states under externally applied pressure.
