Electronic and molecular structure calculations of 29 selected La@C76 isomers are presented. The obtained energies and structural parameters are used for prediction of the temperature dependence of their equilibrium molar fractions. The Gibbs energies are used for the evaluation. The results can be applied to the conventional electric-arc preparation technique. At experimentally relevant temperatures 1500–2000 K not only the prevailing isolated-pentagon-rule (IPR) satisfying isomer, but also a non-IPR one could be accessible to isolation.