Biological hydrogen production from organic wastes is a less expensive, less energy-demanding, and environmental-friendly process. Pure monoculture delivers low H-2 content and low yield; these limitations are overcome by a defined co-culture system, which outperforms mixed cultures with increased H-2 yield. The strategies used in co-culture systems for increasing H-2 production have been discussed in this review. The strategies include hydrolysis of a variety of complex substrates, such as cellulose, molasses, crude glycerol, and algal biomass into simple fermentable sugars for increased H-2 yield by eliminating the use of exogenous enzymes. The strategies can bring geographically distant isolated microorganisms from different sources to coexist for simultaneous utilization of substrate and end metabolites into H-2 production of 99.99% purity without the expenses of reducing agents. In the case of maximum hydrogen production using co-culture strategies, Clostridium, Enterobacter, and photo-fermenting bacteria in a consolidated bioprocess system will result in increased H-2 yield. A co-culture system is more feasible to achieve theoretical H-2 yield with high conversion efficiency of organic wastes, enhance the economic viability of H-2 production, provide better effluent treatment quality, and concurrently address the limitations of H-2 production. Copyright (c) 2015 John Wiley & Sons, Ltd.