In an attempt to carry out a systematic study on the behavior of the photospheric abundances of Li, C, and O (along with Fe) for Hyades main-sequence stars in the range of 5000–7000 K, we conducted an extensive spectrum-synthesis analysis applied to four spectral regions (comprising lines of Fe-group elements, Li I 6708 line, C I 7111–7119 lines, and O I 6156–8 lines), based on the high-dispersion spectra of 68 selected F–G type stars belonging to this cluster. The abundances of C and O turned out to be fairly uniform in a marginally supersolar level, such as like the case of Fe: [C H] 0.15 ( 0.08), [O H] 0.22 ( 0.14), and [Fe H] 0.11 ( 0.08), suggesting that the primordial abundances are almost retained for these elements. Strictly, however, they show a slightly increasing trend with a decrease in (typically on the order of 10 dex K ); while this might be due to an improper choice of atmospheric parameters, we found it difficult to give a quantitatively reasonable explanation. Regarding Li, we confirmed the well-known -dependent trend in the Li abundance reported so far (a conspicuous Li-trough at 6300 K 6700 K and a progressive decrease toward a lower at 6000 K), which means that the surface Li of Hyades stars is essentially controlled only by ; other parameters, such as the rotational velocity, are almost irrelevant.