Mannooligosaccharides (MOS) are considered as potential prebiotics that have health benefits. Production of high-purity mannooligosaccharides acquires expensive multiple purification steps, so limits application capability of these products. In this research, a recombinant Aspergillus niger BK01 mannanase was used to hydrolyze residual copra pulp. The optimal MOS-producing conditions (pH of 3.5, temperature of 70oC, enzyme/substrate ratio of 40 U/g, and hydrolysis time of 20 hours) were determined. Under these conditions, MOS yield reached approximately 38 percent. The product was rich in mannooligosacchrides and contained no mannose. It had antioxidant activity and ability to increase the growth of probiotics Lactobacillus spp. MOS derived from copra could be a potential benefit additive for food and feed productions.