The purchasing function has played an important part in the financial performance of a company, since the value of purchase and contracting of goods and services has emerged as a significant portion on their profit and loss statements, deserving, increasingly, management attention as a strategic activity. In this context the activity of supply has been expanded in the purchase or contracting of goods and services process not only focusing on the value of products and services, but also in the relationships within the supplier market. Kraljic s Portfolio Model, submitted in 1983, is a good way to translate the sourcing strategy theme as it sorts all purchasing and contracting items in terms of profit impact and risk of supply, developing four categories of items associated to their markets. Although Kraljic s portfolio model has become much more accepted, it has been the target of criticism as it can be seen in the literature, among which we highlight the matrix s dimensions measurement subjectivity, during the classification of Item s purchasing stage. In this dissertation it was emphasized the classification of items of goods and services, the first step of the Kraljic s Portfolio Model, which sought to demonstrate the practical application of a measurement method, called one-by-one, through an oil and gas industry s company case study, which sets quickly and objectively the measure high and low for the supply risk and profit impact, with a view to its placement in one of four groups of items. It was also sought to introduce evidences about the possibility of using purchases portfolio model in companies whose purchases and contracts are governed by Decree 2745/98, Simplified Regulation Bidding Process of Petróleo Brasileiro SA - PETROBRAS.