The lyotropic liquid crystalline phases of surfactants exhibit a rich polymorphism of structures that have long-range periodicities and whose characteristic repeat distances range from 2 to 15 nanometers. The electrochemical reduction of platinum sails confined to the aqueous environments oi these phases leads to the deposition oi platinum films that have a well-defined long-ranged porous nanostructure and high specific surface areas. These results suggest thai. the use oi liquid crystalline plating solutions could be a versatile way to create mesoporous electrodes for batteries, fuel cells, electrochemical capacitors, and sensors.