We present a rapid etch method to surface-micromachine nanochannels with integrated noble metal electrodes using a single metal sacrificial layer. The method is based on the galvanic coupling of a chromium sacrificial layer with gold electrodes, which results in a 10-fold increase in etch rate with respect to conventional single metal etching. The etch process is investigated and characterized by optical and electrochemical measurements, leading to a theoretical explanation of the observed etch rate based on mass transport. Using this explanation we derive some generic design rules for nanochannel fabrication employing sacrificial metal etching.