The life cycle inventory (LCI) of the electric power generation plays a vital role on LCIs of the industrial products. However there are no formal life cycle assessment (LCA) studies in Indonesia so far due to limited number of LCA expertise and lack of sufficient databases relevant to domestic conditions. The objective of this study is to introduce life cycle assessment (LCA) method for Indonesian electric power generation systems and to establish LCI for electricity grid mix of Indonesia. In this paper, the emissions of CO₂, SO₂, NO_x, CO, CH₄, NMHC, N₂O, Dust (SPM), Ni, As, Cd, Cr, Hg, Pb, Zn per kWh of electricity generated were estimated for the systems using a combined method of process analysis and input-output analysis. Additional analyses on the impacts of emerging and future technologies as well as the influences of changes of various assumptions are helpful for a better understanding. As the result, the LCA evaluations are discussed for further ecological improvement.