To address the problem of information asymmetry in renewable electricity markets, European governments have introduced certification schemes. While certification appears to be an increasingly important trade mechanism for renewable electricity, it is unclear to what extent certificate markets are functioning properly. In addition, countries have chosen very different designs for their certification schemes. In order to assess the performance of markets for Guarantee of Origin certificates in twenty European countries, we construct four market performance indicators and analyse their development over 2001-2016: the chum rate, price volatility, the certification rate and the expiration rate. We also investigate the relationship between market performance and two design features of certification schemes: the public/private nature of the certifier and the presence of an international standard. We find that, despite increasing shares of renewable electricity are being certified, certificate markets suffer from poor liquidity and very volatile prices. In addition, we conclude that adopting an international standard fosters the development of certificate systems.