Abstract: A high-pressure, double-chamber, fan-stirred, large-scale explosion facility is proposed for measurements of laminar and turbulent burning velocities, S L and S T, of centrally-ignited hydrogen and carbon monoxide syngas/air mixtures over an initial pressure range of p = 0.1–1.0 MPa. Results show that lean syngas laminar flames at elevated pressure are highly unstable resulting in cellular structures all over the expanding flame front surface, where S L∼p −0.15 having a relatively modest decrease with pressure as compared to lean methane flames where S L∼p −0.50. Contrarily, as to lean syngas turbulent flames, values of S T increase with increasing pressure (S T∼p 0.15) at a fixed r.m.s. turbulent fluctuating velocity (u′ ≈ 1.4 m/s). Moreover, it is also shown that increasing u′/S L is still a way much more effective in increasing values of S T/S L than increasing pressure. Finally, discussions are offered and area for further studies identified. [Copyright &y& Elsevier]