In this paper we consider the five dimensional cosmological model with variable gravitational and cosmological constants in the presence of perfect fluid in Kaluza-Klein theory of gravitation. The exact solutions of the field equations are obtained by using the gamma law equation of state p = (γ − 1)ρ in which the parameter γ depends on scale factor R. A unified description of early universe is presented with the assumption = βH 2 in which inflationary phase is followed by radiation dominated phase. The various physical aspects of the cosmological models are also discussed in the framework of higher dimensional space time.

In this paper we present a number of classes of solutions of the Einstein's field equations with variable G, and bulk viscosity for a Kaluza-Klein type of cosmological model. The solutions are obtained by using γ -law equation of state p = (γ − 1)ρ, where adiabatic parameter γ -varies continuously as the universe expand. A unified description of the early evolution of the universe is discussed with number of possible assumption on the bulk viscous term and gravitational constant in which an inflationary phase followed by radiation-dominated phase. We also investigate the cosmological model with constant and time dependent bulk viscosity along with constant and time dependent gravitational constant. In all cases, the cosmological constant found to be positive and decreasing function of time which supports the results obtained from recent supernovae Ia observations. The important physical behaviour of the early cosmological model has also been discussed in the frame work of higher dimensional space-time.

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The field equations with variable cosmological and gravitational constants are consider in the presence of perfect fluid for Kaluza-Klein type cosmological model. The exact solutions of the field equations are obtained by using the gamma law equation of state p = (γ − 1)ρ in which the parameter γ depends on scale factor R. The functional form of γ (R) is used to analyze a wide range of cosmological solution at early universe for two phases in cosmic history: inflationary phase and radiation dominated phase. The corresponding physical interpretation of cosmological solution are also discussed in the framework of higher dimensional space time.