Micro hollow spheres are spherically symmetrical particles consisting of at least two phases. Their sales are continuously increasing because of a large number of potential applications that have been well known since long. While most of the current needs for micro hollow spheres are met by inorganic by-products of combustion processes (cenospheres), the preparation of tailor-made hollow sphere structures is mainly determined by processes like spray-drying as well as dripping, emulsion and suspension techniques. Surface phenomena play an important role as far as formation, properties and stabilities of micro hollow spheres are concerned. Template techniques can be used to yield structures that have not been available so far. Modeling and simulation of the formation processes are useful tools to understand the formation mechanisms and to simplify the scale-up.