The deal is expected to be completed by the end of 2015 and will be integrated into Thermo Fisher's Laboratory Products and Services segment.
Based in Heysham, UK, Alfa Aesar is part of Johnson Matthey and has 480 employees. Among its product offerings are chemicals for DNA-, RNA-, and PCR-based research, products for DNA and protein labeling, and proteomics reagents and kits.
Also, Alfa Aesar offers immunology products, antibodies, cell culture reagents, and other technologies.
The firm operates in the US, Germany, China, South Korea, and India and generated £78 million in sales in 2014.
Thermo Fisher President and CEO Marc Casper said the acquisition enhances his firm's existing portfolio of chemicals, solvents, and reagents "to support virtually every laboratory application".