Marathon Fusion

Growing fusion's fuel supply while co-producing gold

Building the highest power density reactor in the world.

The fuel cycle determines whether fusion energy is economically viable. Marathon is developing the next generation of fuel-cycle technology for commercial fusion.

Fusion-spectrum neutron testing for the structural materials fusion power plants will be built from

Press coverage and announcements from Marathon Fusion

Full-stack nuclear fusion

Marathon Fusion introduces a method to produce the cancer-treatment isotope **Terbium-149** using a stable gadolinium precursor. This approach aims to eliminate a long-standing supply bottleneck by leveraging common medical cyclotrons. The research could expand access to Tb-149, a potential breakthrough in targeted cancer therapies.

Sep 2026Yahoo FinanceNews article

Marathon Fusion successfully enriches lithium and hydrogen isotopes, advancing its reactor fuel technology. The seed-stage climate-tech startup now targets a Series A funding round to scale its innovation. The breakthrough addresses critical challenges in fusion energy development.

Aug 2026Heatmap NewsNews article

Nuclio Media reports a potential breakthrough in producing **terbium-149**, a radioisotope long studied for targeted cancer therapy. Researchers have developed a new production method that could address past challenges, making its use in medical treatments more feasible. The advancement aligns with growing demand for precision oncology solutions in radiopharmaceuticals.

Jul 2026Nuclio MediaNews article

Marathon Fusion, a San Francisco-based startup, proposes generating gold as a secondary output of nuclear fusion. The company’s co-founder outlines an unvalidated method where gold forms during the superheating of atoms in fusion reactions. While peer review is pending, the approach frames gold production as a lucrative side effect rather than the primary goal.

Aug 2025The AtlanticNews article