Abstract: The drift theory of fossil fuel production is associated with the plant material transported with stream of water from one place to another, and finally get deposited in a place of swamp having the suitable condition like sediments. The evidence of drift theory is provided by the sedimentary deposits of coal and other fossil fuels. To trace the origin of formation of fossil fuels in the earth’s crust, we consider the application of laws of thermodynamics using the Hess’s Law, Gibb’s free energy, heat enthalpies, and particularly the deoxygenation parameters to study the transformation of plant materials into the fossil fuels. Here, I elucidate the concept of thermodynamics linked intricately with the development of fossil fuels and the phenomena of photosynthesis, a prerequisite in the thermal analysis of fossils.