A series of blends with various compositions was prepared on the basis of polysulfone, polyethersulfone, and polyimide. These blends were characterized by different techniques, including Fourier transform IR spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, and tensile stress-strain measurements. The results obtained allowed for certain conclusions regarding blend compatibility. In addition, the mechanical properties were subjected to an experimental test design to measure the blends for tensile break strength and Young's modulus with a computer program, which eventually enabled us to obtain the surface response equations of both properties and also to predict the optimum composition presenting the best mechanical behavior. (C) 2004 Wiley Periodicals, Inc.