Thermochemical studies of metal compounds of ‘s’ and ‘f’ block elements and those of organometallic compounds are of immense importance because not only they furnish invaluable information regarding analysis and characterization of the compound thermodynamically but also give vital information regarding ‘specific enthalpy’ and ‘enthalpy density’. Thus viability and analysis of input and output of energy is of prime concern before any process or reaction or for that matter if any engine or industry is being set up because after all it is the process or reaction which takes place inside the engine. As the globe is gradually but certainly moving away from fossil fuel or carbon-based energy production as it immensely pollutes the environment due to evolution of greenhouse gases into the environment and contribute towards global warming, it is but necessary to evaluate the impact assessment of the pollutants on the environment before any engine or industry is being developed or installed. It is in this perspective that the thermochemical studies of metal compounds of ‘s’ ‘p’ ‘d’ and ‘f’ block elements and those of organometallic compounds become extremely important as it clearly identifies and defines the products as well as absorption and evolution of energy involved therein.