The Metals Company (TMC) is pioneering a new source of critical minerals needed to scale up battery production and energy storage globally. A vast resource of nickel, copper, cobalt, and manganese is contained in polymetallic nodules that sit unattached on the seabed, four kilometers below the surface in an area of the Pacific Ocean called the Clarion Clipperton Zone. TMC’s flowsheet to produce these metals from the nodules involves initial pyrometallurgical processing to produce a nickel-copper-cobalt matte, which is further refined to battery-grade sulfates and copper metal using a conventional hydrometallurgical process. This paper provides an overview of the project, the hydrometallurgical flowsheet, and the associated outcomes from a bench-scale testing program undertaken at the SGS laboratories in Lakefield, Ontario. The hydrometallurgical flowsheet being developed is based on existing processes used commercially for treating platinum group metal-containing matte. It consists of a multistage leach process that produces a nickel-cobalt liquor with low copper, which is further refined into separate nickel and cobalt streams to produce high purity, battery-grade sulfate crystals. The process also produces a copper-rich liquor that feeds copper electrowinning for the production of copper cathode. This multistage leach process includes both atmospheric and pressure leaching and was demonstrated to achieve greater than 99% extraction of nickel, cobalt, and copper from the matte. Both the nickel and cobalt sulfate specifications will be presented and will show that the achievable purities of these products are comparable to those observed in present market battery-grade sulfates.