  The bulk viscosity coefficient of hadronic matter has been estimated in this
present work, where the thermodynamical equilibrium quantity like speed of
sound in the medium has been obtained by using standard hadron resonance gas
model. Whereas, the non-equilibrium quantity like thermal widths of medium
constituents have been calculated in the framework field theory at finite
temperature. Our values of bulk viscosity coefficient are in agreement with
some earlier estimations.
