Synairgen PLC (AIM:SNG, OTC:SYGGF) said Joseph Colliver will succeed John Ward as chief financial officer effective 6 November.
Colliver comes to Synairgen with experience in senior finance and non-executive roles, most recently in life sciences.
Ward will ensure an "orderly handover" after almost 20 years with the company.
"Joseph's many years of listed company experience, including in the healthcare sector, will stand us in good stead as we progress towards the clinic with our SNG001 strategy," said chief executive Richard Marsden.
"I'd like to thank John for his steadfast commitment, loyalty and support to both me and the board over many years. We wish him the very best for the future."
Synairgen's lead asset is SNG001 (inhaled interferon beta) for severe viral lung infections.