2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/56737We obtained a new representation of a solution of the heat conduction equation with boundary condition of the third kind for a layer. The result is presented as a superposition of fundamental solutions for an unbounded system with variable coefficients, the explicit form of which is given. We consider the well-known problem of the evolution of the temperature field initially uniformly distributed in a layer. The distribution of the temperature field is represented in terms of the obtained functions.16 pages, 2 figures, RevTeXMathematical Physics35K05; 35K20text