Acting on behalf of landlords Marcol, property specialists VSL & Partners arranged for the biotech business to renew its existing 3,900 sq ft of space on the ground floor of Northbrook House and take on an additional 5,200 sq ft on a new five-year lease.
Staff will relocate from the MWB serviced offices at Oxford Science Park.
VSL associate director Duncan May said: “Once again we are seeing the strength of the Oxford biotechnology market with Circassia an excellent example of how the sector is growing.
“Clearly its location on the Science Park is reaping benefits and Oxford can only benefit from the continued success of an international business.”
Earlier this year Circassia was given a major boost after drugs giant AstraZeneca announced it was taking a £40m stake in the company.