X-energy expands Gaithersburg headquarters to 145,000 square feet

X-energy, a clean energy company specializing in nuclear reactor and fuel design technology, is expanding its planned headquarters in Gaithersburg, Maryland. The company has added approximately 24,000 square feet to its footprint at the Washingtonian Center, bringing its total space at the building to roughly 145,000 square feet.

The expansion follows X-energy’s July 2025 announcement to consolidate two Rockville offices into a single headquarters. The move is expected to retain 260 full-time jobs in Montgomery County and create more than 525 new positions over the next six years.

The expansion also assists landlord Prime US REIT in filling space previously vacated by tenants such as Sodexo and Covance. The Montgomery County Economic Development Corporation supported the decision through local incentive programs and workforce resources.