  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 have
searched for the J = 0 -- 1 rotational line of lithium hydride at 444 GHz
(redshifted to 263 GHz). The line, if detected, is optically thin, very narrow,
and corresponds to a column density of N(LiH) = 1.6 10$^{12}$ cm$^{-2}$ for an
assumed excitation temperature of 15 K, or a relative abundance LiH/H$_2 \sim$
3 10$^{-12}$. We discuss the implications of this result.
