According to the current understanding of the evolution of the Universe the presently observed state of the Universe is the result of expansion from an extremely dense and extremely hot singular origin. Describing that evolution of the Universe by means of the standard cosmological model, based on the ‘big-bang’ hypothesis, cosmological nucleosynthesis occurs at the appropriate temperature in the course of expansion and goes on until the decreasing temperature stops nuclear reactionsNuclear, reactions. No significant cosmological nucleosynthesis beyond helium-4 occurred due to the instability gaps at mass number 5 and mass number 8 as well as the constraints set by the present universal density and temperature. However, it is well-known that ‘big-bang’ nucleosynthesis results in the production of lithium-7 in amounts comparable to the solar system abundance of this nucleus. Some general features of the cosmological nucleosynthesis are listed in Table 2.1 and Figs. 2.1 and 2.2.