Cogeneration involves production of both thermal energy as well as electrical energy. The thermal energy is generally realized by production of steam, which can be used as process steam. Gas turbine used for marine propulsion can also have cogeneration applications through the utilization of gas turbine exhaust energy for steam generation purposes. Gas turbine blade cooling is critical to reliable operation of gas turbine based power utilities. A thorough literature review suggests that air-film cooling is one of the most widely used blade cooling techniques. The aim of the present study is adoption of few previously developed air-film cooling based gas turbine blade cooling models (without considering radiative heat transfer) and compare them with proposed gas turbine model for estimating blade coolant mass fraction which considers radiative heat transfer from gas turbine blade surface. Also the study focuses to extend this article towards analysis of gas turbine based cogeneration cycle with single-pressure heat recovery steam generator. The proposed blade cooling model is expected to give a more realistic prediction of blade coolant mass fraction. Results have been plotted based on proposed model in terms of blade coolant mass fraction, gas turbine cycle specific work, fuel utilization efficiency, power-to-heat ratio, which are the function of both compressor pressure ratio and turbine inlet temperature. The paper also describes the possibilities of improvements in gas turbine efficiency and power output by advancement in blade material technologies and adoption of single crystal blades. The paper further carried out the exergy analysis to highlight component-wise exergy destruction. The second law efficiency for the gas turbine has been found to be ≈ 35% (at TIT =1750K) while combustor is the cycle component with maximum exergy destruction.