  In this paper we have studied Kaluza-Klein string cosmological model within
the framework of f(R; T) theory of gravity, where R is the Ricci scalar and T
is the trace of the stress energy momentum tensor. We have obtained the
solution of the corresponding field equations by using a time varying
deceleration parameter. We also discussed various physical and dynamical
properties of the model. The variation of different cosmological parameters are
shown graphically for specific values of the parameters of the model.
