We present new high resolution spectroscopic observations of the intermediate age ( \sim 2 Gyr ) open cluster NGC~752 .
We investigate the Li vs . T _ { eff } distribution and we obtain a new accurate determination of the cluster metallicity .
We compare the results for NGC 752 with other intermediate age and old clusters spanning the age range from the Hyades ( \sim 0.6 Gyr ) to NGC~188 ( \sim 6–8 Gyr ) .
We find that NGC 752 has a solar iron content ( [ Fe/H ] = +0.01 \pm 0.04 ) , at variance with early reports of sub–solar metallicity .
We find that NGC 752 is only slightly more Li depleted than the younger Hyades and has a Li pattern almost identical to that observed in the \sim 2 Gyr old IC~4651 and NGC~3680 .
As for the latter clusters , we find that NGC 752 is characterized by a tight Li vs . T _ { eff } distribution for solar–type stars , with no evidence for a Li spread as large as the one observed in the solar age solar metallicity M~67 .
We discuss these results in the framework of mixing mechanisms and Li depletion on the main sequence ( MS ) .
We conclude that the development of a large scatter in Li abundances in old open clusters might be an exception rather than the rule ( additional observations of old clusters are required ) , and that metallicity variations of the order of \sim \pm 0.2 dex do not affect Li depletion after the age of the Hyades .