A metal dicyanamide material Ni[N(CN)(2)](2) (Ni(dca)(2) dca = dicyanamide) was found to exhibit negative linear compressibility (NLC) along its a-axis over the pressure range of 0-1.1 GPa by performing in situ high pressure angle dispersive X-ray diffraction (ADXRD) experiments. First-principles calculations revealed that the Ni-N C-N chains forming wine-rack-like frameworks was the mechanism for the NLC phenomenon.