SmFeN micro particles (MPs) were applied to matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). The co-matrix between SmFeN MPs and organic matrix molecules, such as sinapic acid and succinamide, was used for MALDI-MS of model peptides. By using the co-matrix, an enhancement of analyte- and matrix-related ion peaks was clearly observed. It was understood that the spectroscopic change of the organic matrix molecules by mixing SmFeN MPs and the irregularities on the MP surface were responsible for the ion peak enhancement by the co-matrix. (C) 2013 Elsevier B.V. All rights reserved.