The electrosynthesis of p-hydroxybenzaldehyde (PHB) from sodium p-hydroxymandelate (SPHM) was investigated and good synthesis conditions were obtained. The electrochemical reactor was a divided filter-press with carbon felt electrodes (anode and cathode). Two different anolytes were used depending on the membrane employed. Thus, a 0.6 M SPHM 2.71 M NaOH solution was used in conjunction with a cationic Nafion(R) 117 membrane while a 0.6 M SPHM in 1.8 M NaOH solution was employed with an anionic Ionac(R) MA-3475 membrane. The electrolysis was carried out at a constant current density of 100 mA cm(-2). A material yield of approximately 90% was obtained at an energy cost of 1.4-1.5 kWh kg(-1) PHB and a production of 49 kg PHB m(-2) day(-1).