Optical responses (luminescence and second harmonic generation) were measured to demonstrate local product formation on the pm scale in combinatorial ceramic samples made by reacting simultaneously 16 or 30 different MO,, oxides or carbonates. Observation of distinct hot spots on the surface of reacted pellets, micrometer thin cuts and desaggregated particles confirm local property formation by the singlesample concept (SSC). Statistical calculations applied to 2D cuts of SSC samples demonstrate, that by reacting micrometer sized starting materials, compounds existing in the large phase space are likely to be formed, because the SSC is providing the starting compositions many times (tents to hundreds) depending on the total number of starting components. (c) 2006 Elsevier Ltd. All rights reserved.