Abstract ¾ XX century culture has emphasized specialization paradigm in all knowledge domains, including Engineering one. World culture, naturally, has increased complexity on globalization times putting real challenge to educators looking for an International Engineer profile for XXI century. On this direction, this paper presents core aspects from a knowledge based educational model - Thematic Oriented Methodology - which is centered in complex modeling axis just to treat knowledge domain. This methodology theoretical orientation, is in accordance with Complex Thought research from UNESCO Edgar Morin itinerant cathedra for XXI century education. The present proposal combines those generic principles enounced by Edgar Morin, and a concrete knowledge modeling tool, born in Informatics - Object Oriented modeling tool. From complex information systems, this informatics tool can be, yet, applied at educational perspective. The central axis of Thematic Educational Methodology is knowledge treatment as a complex system, integrating vertical and horizontal knowledge categories. This facilitates pedagogic and harmonic integration of contents, from abstract issues like social, ethical and cognitive to concrete issues like math’s and physics, or even computer programming. Here, it seems crucial to discuss about a definition of complexity that is, at first, quite ambiguous word, if they are considered different kinds of knowledge paradigms. Definition of complexity, under open knowledge paradigm, added with complexity of object of study definition, constitutes a contribution to international perspective in Engineering curriculum. They are presented some practical examples combining abstract and concrete issues related with an Informatics discipline for Engineering course beginners. It is presented an example of thematic definition for a complex project in Environmental Engineering. Finally, it is analyzed the presence of technology as educational tool support and what is the role of Informatics in techno carriers. Informatics can be, not only a concrete tool support, but much more. it can, also, be a potential tool for complex systems modeling like Engineering educational system. Putting all together is the aim from XXI integrative spirit in Engineering education and also from the presented methodology.