The C (1)Sigma(+) excited electronic state of (LiH)-Li-6 and (LiD)-Li-7 isotopomers has been studied by a pulsed optical-optical double resonance fluorescence depletion spectroscopic technique, in which a band-resolved laser-induced fluorescence detection scheme was used. Forty-two.(LiH)-Li-6 vibrational (nu = 2-43) levels and fifty-five (LiD)-Li-7 vibrational (nu = 4-58) levels have been separately observed. The absolute vibrational numbering of the (LiD)-Li-7 C (1)Sigma(+) state is identified via a comparison between observed term values and those calculated with a hybrid potential energy curve reported previously for the (LiH)-Li-7 C (1)Sigma(+) state. Among the highest observed vibrational levels, the highest observed rovibrational levels are respectively the (43,5) level for (LiH)-Li-6 and the (58,8) level for (LiD)-Li-7, compared to the level (43,8) reported previously for the (LiH)-Li-7 case. The spectral term values for the vibrational levels lying above nu = 33 for (LiH)-Li-6, and those above nu = 44 for (LiD)-Li-7, occur in an irregular order. The nu = 34, J = 0 level of (LiH)-Li-6 and the nu = 45, J = 0 level of (LiD)-Li-7 lie mainly in the inner, small well. The term values for the observed rovibrational levels, for 2 less than or equal to nu less than or equal to 32, 0 less than or equal to J less than or equal to 11 of (LiH)-Li-6 and for 4 less than or equal to nu less than or equal to 44, 0 less than or equal to J less than or equal to 13 of (LiD)-Li-7, in the outer ionic well are described by a set of Dunham-type coefficients. Together with previous observed term values of (LiH)-Li-7, a combined isotopomer Dunham-type analysis has been performed, and five hydrogen and three lithium mass-dependent Born-Oppenheimer breakdown correction terms for the C (1)Sigma(+) state are determined.