Described herein are direct liquid fuel cells with an alkaline anodic fuel stream including a solution of liquid fuel such as alcohols, ethers, glycols or compounds of hydrazine, and an acidic cathode oxidant stream including a solution of a suitable oxidant such as hydrogen peroxide or a gas steam with 1% to 100% O2. These cells are used as primary stationary and/or mobile power sources and also function in a secondary role as range extenders when coupled with a primary power source.