The ECPA was set up in 1986 to 'record, analyse and improve the conduct of public affairs' in European Union institutions.
Based at Surrey University, the body conducts research programmes and training each year for PA practitioners, civil servants, and managers and staff of NGOs.
Brussels-based Jonnaert set up P&G's European PA office in the Belgiuan capital ten years ago and became deputy chairman of the ECPA in 2000.
ECPA faces issues such as the implications for governments and businesses of the EU's planned eastwards enlargement; the increasing take-up across the EU of corporate social responsibility initiatives; and changes to the EU's regulatory framework.
He said: 'It's important to continue the research we have built up over the years. It's also important to ensure that research carried out is relevant to current business needs. There's always a danger that research can become insular, so it's crucial that it can add real value to companies.'
He added: 'There is an increasing demand for companies to make themselves more transparent to governments and vice versa.'
Jonnaert replaced former chairman Henry Stenson - Ericsson vice-president of corporate comms - in the chairman's role two weeks ago. In accordance with the ECPA's rotation system, Stenson becomes deputy chairman of the management board.