We present mid-IR observations of a sample of very low-mass stars and brown dwarfs in the Upper Scorpius association. The main goal of these observations is to derive the disk frequency and the disk properties of the sample in order to shed light on brown dwarf formation theories. The observations have been performed with VISIR at the Very Large Telescope (VLT, Paranal). A total of ten targets were observed and six were detected. In this paper we show preliminary results for two of them: DENIS-PJ160334 and DENIS-PJ161939. While the former shows mid-IR fluxes consistent with pure photospheric emission, the latter displays strong mid-IR excesses which are probably related with a circumstellar disk. Based on observations collected at ESO/VLT (Paranal) under program ID 075.C-0148(A)