  We report the possible detection of a Li I 6708 AA line enhancement during an
unusual long-duration optical flare in the recently discovered, X-ray/EUV
selected, chromospherically active binary 2RE J0743+224. The Li I equivalent
width (EW) variations follow the temporal evolution of the flare and large
changes are observed in the intensity of the line. The maximum Li I enhancement
occurs just after the maximum chromospheric emission observed in the flare. A
significant increase of the 6Li/7Li isotopic ratio is also detected. No
significant simultaneous variations are detected in other photospheric lines.
Neither line blends nor starspots seem to be the primary cause of the observed
Li I line variation. From all this we suggest that this Li I enhancement is
produced by spallation reactions during the flare.
