IntroductionLife Cycle Assessment (LCA) is an assessment method used to evaluate the environmental impacts of technologies from "cradle to grave" and can be performed on both products and on processes (Huntzinger & Eatmon, 2008). The purpose of this report is to critically evaluate selected published studies on product life cycle assessment. The product selected for this report is cement and below are the selected published studies that need to be critically evaluated: A Life Cycle Assessment of Portland Cement Production: Comparison of the Traditional Process with Alternative Technologies (2008) Deborah N. Hintzinger , Thomas D EatmonImplementation of best available techniques in cement production: a life cycle assessment study (2012)Cesar Valderrama, Ricard Granados, Jose Luis Cortina, Carles M Gasol, Manel GuillemEvaluation of studiesIn order to evaluate the studies, the The most obvious primary objective must be to ensure that the life cycle assessment is consistent with the standard to which it adheres and refers. Both studies refer to the same standard (ISO 14044) which helps to compare and evaluate each study lending itself to the critical evaluation of each. Any effective LCA must involve the following:1. Defining the objective and scope of the phases2. Inventory Analysis3. Impact assessment4. And interpenetration of results Product and process LCAs should use the same functional unit and equivalent methodological considerations such as performance, system boundaries, data quality, assignment procedures, decision rules and impact assessment. It is also specified that any differences between systems/products or processes regarding the above must be identified and reported. Both studies…… half of the article…… associated with the use of BAT for the clinker production process are critically analyzed below. Evaluating environmental performance and considering the LCA methodology proves to be an appropriate process. LCA provides a wide range of improvements through the installation of BAT techniques and this is highlighted in damage assessment and comparison with older production lines. Concluding the critical review of such studies, each report adheres to the compliance of the relevant ISO standard. Accepting some minor details and limitations of the studies, the report proves adequate in the sense that it is fit for purpose and quite transparent and consistent in terms of reporting. Each of the facts presented and assessments made rest on a factual basis that indeed possesses great scientific and technical stature. References (Weidema, 1997) (Huntzinger & Eatmon, 2008)