  A general geometric construction of a generic null hypersurface in presence
of torsion in the spacetime (Riemann-Cartan background), generated by a null
vector $l^a$, is being developed here. We then explicitly define and structure
various corresponding kinematical quantities. The dynamics of the null surface,
particularly given by $\hat{G}_{ab}k^al^b$, is also discussed. The later one is
constructed under the {\it geodesic constraint} condition. This yields a
relation among the rate of change of expansion scalar corresponding to
auxiliary null vector $k^a$ and various kinematical entities on the null
surface. Using this relation we show that the Einstein-Cartan-Kibble-Sciama
equation (which provides the dynamics of the metric and the torsion tensor) on
this null hypersurface acquires a thermodynamic interpretation. The
thermodynamic entities like temperature, entropy density, energy and pressure
are properly identified. In the whole analysis we adopt the geometrical field
interpretation of torsion and all discussions are done in a covariant manner.
