  We present the first mid-infrared (MIR) detection of a field brown dwarf (BD)
and the first ground-based MIR measurements of a disk around a young BD
candidate. We prove the absence of warm dust surrounding the field BD LP
944-20. In the case of the young BD candidate Cha Ha2, we find clear evidence
for thermal dust emission from a disk. Surprisingly, the object does not
exhibit any silicate feature as previously predicted. We show that the flat
spectrum can be explained by an optically thick flat dust disk.
