The aims of this PhD research were to investigate the nature of environmental pollution in the Libyan Cement and Iron & Steel Industrial Sectors, identify associated environmental improvements from abatement measures and to develop an approach by which to measure the yield returns on such environmental investments. The study reviewed a range of research literature related to three key areas that form the core foundation of the research. These were investment theory, environmental issues and imputing values for non-market assets. A set of criteria was developed and adopted for searching, selecting and reviewing the research literature related to these areas. Using a two case-study approach, data collection methodologies were carried out by structured face-to-face interviews with thirty-three environmental managers and financial managers of the Libyan Cement Company (LCC) and the Libyan Iron & Steel Company (LISCO). The data collection and analysis involved identifying and assessing environmental pollution concerns within each company and the corresponding improvements in environmental performance from the abatement measures. The research developed cost benefit analysis valuation techniques to award monetary values to the identified environmental productivity improvements, measured in percentage dust particulates reduction, gas emission reduction, and water percentage usage and solid waste efficiency improvements. Under the cost benefit approach, the research determined the yields on the environmental investments by the use of hedonic price valuation. Sensitivity analysis was used to determine the calculated yields for a range of estimated productivities and discount rates to reduce uncertainty in the estimations. Experimentation with a range of values offered insights into yields under different situations. The study results identified the impacts relating to air pollution, liquid pollution, and solid pollution and valued those that had economic significance and for which data was available. The interview findings revealed that the mam environmental issues of the LISCO Company was water usage and the quantity of solid waste, while the main environmental issues of LCC Company was air pollution, predominantly in the form of dust and gas emissions. The environmental investment returns of these two companies were higher than the interest rate in Libya. The study contributed to knowledge in the environmental management field. It furthermore fills the gap in knowledge in environmental investments in the Libyan context.