A z-gradient system for NMR diffusion measurements with intensive pulsed field gradients was redesigned. The gradient field of an actively screened gradient coil was optimized using finite element analysis. The gradient system was constructed with glass ceramic as coil support material. It does not show any background H-1 NMR signal and has a high current-to-gradient conversion factor of 0.37Tm(-1)A(-1). The functionality of the system for studying slow diffusion processes in interface systems is demonstrated by observing isotropic and anisotropic diffusion in aqueous solutions of a PEO-PPO-PEO triblock copolymer and of methane in two different microporous crystalline absorbencies.