Caseinates are traditionally manufactured by precipitating caseins using acid, thoroughly washing the precipitate and then neutralizing the casein curd with alkali, which requires very specialized equipment. The objective of this study was to develop an innovative process utilizing spiral filtration to produce a soluble casein product that would act as a caseinate alternative. Stable casein dispersions were prepared by sufficient acidification of pasteurized skim milk to solubilize the colloidal calcium phosphate (CCP), but avoid aggregating the caseins. The acidified skim milk was processed at ambient temperature using microfiltration /diafiltration to remove serum proteins, lactose, and the soluble minerals. Next the soluble casein product was neutralized with 40% NaOH and spray dried. Compositional analysis, SDS-PAGE, and turbidity measurement were used to characterize the casein product. Our results showed that acidification to pH ~5.3 solubilized the majority of CCP and allowed the removal of calcium during membrane processing. Acidification of the diafiltration water helped to maintain the narrow target pH range throughout the extensive diafiltration. The microfiltration process, temperature and pH were all optimized to promote casein retention and avoid temperature and /or pH-induced casein aggregation. The casein isolate powder had ~93% of crude protein (dry basis), 0.08% calcium, 0.37% lactose, 1.60% fat and casein accounted for 97% of the crude protein. When rehydrated to a total solids content of 5% (w/v), our casein product was less turbid compared with commercial sodium caseinate. This novel process looks promising for the production of a soluble casein product.