The reciprocity relation in solid state NMR has been extended to include the effects of spin-lattice relaxation in the rotating frame. This method was successfully applied to the experiments of Hartmann-Hahn cross polarization, making the originally non-quantified NMR spectra quantitative. In addition, it provides detailed dynamics of cross polarization that is often obscured by spin-lattice relaxation in the rotating frame and by some other effects. Published by Elsevier B. V.