Nickel sulfide-reduced graphene oxide (RGO) composite powders with spherical shapes are prepared by a one-pot spray pyrolysis process. The optimum mole ratio of nickel nitrate and thiourea to obtain nickel sulfide–RGO composite powders with high initial capacities and good cycling performance is 1:8. The bare nickel sulfide and nickel sulfide–RGO composite powders prepared directly by spray pyrolysis have mixed crystal structures of hexagonal α-NiS and cubic Ni3S4 phases. The bare nickel sulfide powders are prepared from the spray solution without graphene oxide sheets. The nickel sulfide–RGO composite powders have sharp mesopores approximately 3.5nm in size. The discharge capacities of the nickel sulfide–RGO composite powders for the 1st and 200th cycles at a current density of 1000mAg−1 are 1046 and 614mAhg−1, respectively, and the corresponding capacity retention measured from the second cycle is 89%. However, the discharge capacities of the bare nickel sulfide powders for the 1st and 200th cycles at a current density of 1000mAg−1 are 832 and 16mAhg−1, respectively. The electrochemical impedance spectroscopy (EIS) measurements reveal the high structural stability of the nickel sulfide–RGO composite powders during cycling.