The 1D Heat Transfer software is used for to study one-dimensional heat transfer (steady and unsteady states). It can be used for the geometries: wall, Lx = width; long cylinder, Lx = length; sphere, Lx = R/3 - with value zero for the flux in the center - and semi-infinite wall, Lx must be greater than the studied position. The software simulates problems with constant and variable properties. The initial condition can depend from the position.