SEARCH FOR LIH IN THE ISM TOWARDS B0218+357

We report a tentative detection with the IRAM 30m telescope of the LiH molecule in absorption in front of the lensed quasar B0218+357. We ha ve searched for the J = 0 --> 1 rotational line of lithium hydride at 444 GHz (redshifted to 263 GHz). The line, if detected, is optically t hin, very narrow, and corresponds to a column density of N(LiH)= 1.6 1 0(12) cm(-2) for an assumed excitation temperature of 15 K, or a relat ive abundance LiH/H-2 similar to 310(-12). We discuss the implications of this result.