The achievement of controlling thermal expansion is important for open-framework structures. The present work proposes a feasible way to adjust the coefficient of thermal expansion continuously from negative to positive via inserting guest Na+ ions or H2O molecules into a GaFe(CN)(6) framework. The guest ions or molecules have an intense dampening effect on the transverse vibrations of CN atoms in the -Ga-N C- Fe- linkage, especially for the N atoms. This study demonstrates that electrochemical or redox intercalation of guest ions will be an effective way to tune thermal expansion in those negative thermal expansion open framework materials induced by low-frequency phonons.