Carbon aerogels with controlled porosity can be obtained by doping Ce and/or Zr into the resorcinol-formaldehyde reaction mixture. As highlighted here, the concentration of metal dopant and the pH of the initial reaction mixture can have a profound effect on the structure, porosity, and physical properties of the resulting aerogel. The Figure shows the morphology of a Ce,Zr-doped carbon aerogel synthesized at pH 7.