AbstractThe production yields for characteristic x‐rays from the bombardment of thick targets by protons are calculated by integrating the x‐ray production cross‐section for each element for the whole range of the protons, taking into account the self‐absorption of x‐rays. A simple approximation which can be applied with a pocket calculator is also presented, using simplified relationships for the energy dependence of the proton stopping power and the x‐ray production cross‐sections. The approximation allows very fast calculations, has an accuracy of better than 5% for low‐energy protons and is also very useful for the first steps in a computer program for PIXE analysis of thick targets, using the method of iterations. The calculated yields are compared with experimental results obtained on thick specimens of pure elements, compound