Several studies have been investigated in the superconducting materials such as critical magnetic field, magnetic field, critical temperature etc. Here, we will discuss the empirical relation between critical magnetic field and temperature for superconductors. Till today, this empirical relation was obtained on the basis of experimental data of superconducting materials. Therefore, we are deriving this empirical relation theoretically by the use of the concept of BCS theory, thermodynamics and magnetic properties for superconductors.