The invention relates to carbon nanotube structures containing both single walled and multi walled carbon nanotubes, and methods for preparing same. These carbon nanotube structures include but are not limited to macroscopic two and three dimensional structures of carbon nanotubes such as assemblages, mats, plugs, networks, rigid porous structures, extrudates, etc. The carbon nanotube structures of the present invention have a variety of uses, including but not limited to, porous media for filtration, adsorption, chromatography; electrodes and current collectors for supercapacitors, batteries and fuel cells; catalyst supports, (including electrocatalysis), etc.