A new procedure for preparing microelectrode ensembles, based on casting an ultrathin microcellular polyacrylonitrile (PAN) insulating foam onto a dense carbonized PAN film, is described. The resulting partially blocked surfaces display the behavioral characteristics of ensembles of recessed microelectrodes (of small depth), with steady-state currents at moderate and long timescales. Cyclic voltammetry and chronoamperometry were used to elucidate the electrochemical behavior, while scanning electron microscopy sheds useful light on the surface microstructure. Square-wave stripping voltammetry is demonstrated for the quantification of nanomolar concentrations of lead using short deposition periods and unstirred solutions. These and other PAN-derived composite electrodes present new opportunities for various electrochemical and analytical applications.