In the increasingly competitive environment of the modern business world, professional and effective procurement management plays an essential role in the strategic success of an organization. Providers of raw materials, components, and services contribute significantly to the overall value generated by their customers, thereby improving their customers' market position. When viewed in this context, a well-defined chemicals purchasing strategy becomes a genuine value driver for a water desalination plant. Trends in the desalination industry directly impact chemical consumption by reducing energy usage, increasing operating efficiencies, and lowering costs while minimizing environmental impact. To meet the emerging challenges of cost and benefit alongside environmental conservation, a comprehensive procurement model needs to be explored. This research aims to provide a comprehensive method for chemicals classification and supplier evaluation, which can be utilized to enhance operational efficiency while reducing costs and risks. Multiple models have been utilized by researchers for classification of materials and economic order placement and procurement, but underlaying factors or measurement indicators vary industry wise. The researcher in this study will explore conceptual model from existing literature and apply on data collected from archives and experts of QIWP to develop a chemical classification and vender selection specifically addressing the issues of procurement of chemicals for water desalination industry of Sultanate of Oman. This research will have two stages. In stage one, the researcher will apply the portfolio model proposed by Kraljic in 1983, and chemicals will be divided into four distinct categories: strategic, leverage, bottleneck, and routine. Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), which is a Multi-Criteria Decision Making (MCDM) method, will be used throughout the classification process. Then based on the results of stage one, stage two will utilize Data Envelopment Analysis (DEA) and Simple Additive Weighting Method (SAWM) to rank suppliers according to their efficiency.