A significant effort is underway to develop biofuels as replacements for non-renewable fossil fuels. Among the various options, hydrogen is an attractive future energy carrier due to its potentially higher efficiency of conversion to usable power, low generation of pollutants and high energy density. There are a variety of technologies for biological hydrogen production; here, we concentrate on fermentative hydrogen production and highlight some recently applied approaches, such as response surface methodology, different reactor configurations and organisms that have been used to maximize hydrogen production rates and yields. However, there are significant remaining barriers to practical application, such as low yields and production rates, and we discuss several methods, including two stage processes and metabolic engineering, that are aimed at overcoming these barriers.