International supplier selection, which is becoming a dominant strategy in an increasing number of sectors, is a multi-criterion decision problem. This study aims to contribute to this contemporary global issue initially by developing a multi-criteria hierarchical model for supplier selection utilizing the analytical hierarchy process (AHP). The AHP model aids decision making by quantifying the relative importance of each criterion and by ranking the suppliers. Secondly, The AHP model is augmented with a linear programming model which aims to maximize the buyer's total value of purchasing through optimal order splitting among suppliers. The augmented model will make it possible for the decision maker to observe the hierarchy of the supplier selection decision criteria, quantify the relative importance rate for each criterion, rank the suppliers, select the best supplier(s) and realize optimal order splitting among suppliers. Thirdly, the model is applied to a Turkish chemical company and an Australian one where the results point to some important differences in the two companies' decision criteria preferences and decision making habits. Although the findings cannot be generalized, this might pave the way for further analyses that will be conducted at country level. Comparative studies might aid not only in supplier selection but also in designing supply chains and supplier strategies.