Micellar casein concentrate (MCC) powders with a protein content of 60% (MCC60) and 85% (MCC85) and a calcium-reduced MCC85 were processed by microfiltration (MF) and diafiltration (DF) of skim milk followed by spray-drying. pH adjustment of the starting milk to 6.2 and MF-retentate to 5.6 prior to MF and DF, respectively, yielded a calcium-reduced MCC85 from which approximately 50% of total calcium had been removed. Calcium reduction improved solubility of MCC85 but did not affect viscosity and caused a small increase in casein micelle size (approximately 15%). The amount of lactic acid required to reach a pH of 4.7 by fermentation was higher for control MCC85 and was further reduced for calcium-reduced MCC85 and fermentation times were notably longer for control MCC85. Acid gels from calcium-reduced MCC85 were stronger than from other products. This study shows the potential of making highly functional calcium-reduced MCC85 products using simple process adaptations.