The proposed manual under the section "Molecular Physics" for students of schools with an increased level of training in physics and mathematics corresponds to modern ideas about molecular motion and its macroscopic manifestations. In addition to applied questions, it contains a complete and consistent presentation of the basic principles of molecular physics. It should be noted the methodically correct construction of the entire section and the inclusion in the manual of mathematical additions on those issues on which the reader, for various reasons, is either insufficiently prepared or is not familiar with them at all.