The 1D Heat Transfer software is used 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. Type of boundary conditions: temperature, flux and convection.