Electrospray ionization mass spectrometry (ESI‐MS) is used to probe the complex formation between tebuconazole (1) and copper(II) salts, which both are commonly used fungicides in agriculture. Experiments with model solutions containing 1 and CuCl2 reveal the initial formation of the copper(II) species [(1)CuCl]+ and [(1)2CuCl]+ which undergo reduction to the corresponding copper(I) ions [(1)Cu]+ and [(1)2Cu]+ under more drastic ionization conditions in the ESI source. In additional experiments, copper/tebuconazole complexes were also detected in samples made from soil solutions of various origin and different amount of mineralization. The direct sampling of such solutions via ESI‐MS is thus potentially useful for understanding of the interactions between copper(II) salts and tebuconazole in environmental samples. Copyright © 2011 John Wiley & Sons, Ltd.