Secondary ion mass spectrometry (SIMS) is based on the bombardment of solids by ions and subsequent mass spectrometric analysis of the ions sputtered from the target. It provides comprehensive elemental and isotopic analysis with extremely high sensitivity, in situ characterization of thin films and three-dimensional distribution of elements at the surface of solid samples. The principle of the technique, some important parameters for analysis and possible applications for the characterization of art objects and ancient materials are discussed; results obtained by SIMS-investigations on naturally weathered medieval window glass of Austria are presented. -- AATA