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Actinide

Focus

Matter, Energy

Stage

Seed

Why we invested

From stone to bronze to iron, materials have defined human history. Up until the 17th century, we simply worked with what we could see and touch. Fire, water, stone, wood. Then we entered the Chemical Age and the 92 naturally occurring elements that make up the periodic table changed everything.

Actinide is building the foundation of the the next material age, the Atomic Age, by manufacturing machines capable of separating matter at the atomic level.

The periodic table isn't the full story

Chemistry treats all atoms of an element as identical. Particle physics proved that they’re not. Every element is actually a family of variants called isotopes, chemically identical but physically divergent. Those divergent properties produce distinct performance characteristics that hold the promise of a wave of next generation materials.

Engineering, not physics

Actinide was founded to make the technology to build with isotopes foundational infrastructure, not bespoke statecraft. With rapid in-house fabrication producing low-cost, modular units, their system is transforming isotope separation from an aging national asset into a scalable industrial platform.

Actinide’s fleet of machines can be tuned to produce thousands of isotopic variants, generating the ingredients for supercritical products such as therapeutics, next-gen chips, and superconducting energy systems.

A lifelong obsesssion

Robert plays multiple musical instruments, is an Eagle Scout, and built the world’s largest private electromagnet in his apartment. Robert and Eric met through a mutual mentor in Austin, Texas. Eric heard Robert rant about the untapped potential of isotopes, and went all-in, moving his family across the state and personally covered years of operating expenses to scale their shared vision of using isotopes to make science fiction reality.

The smallest variations in matter unlock the largest possibilities

Chemistry provides 92 naturally occurring elements, whereas the isotope universe is a minimum of 3,000 distinct atomic units. Systematic access to isotopes will dramatically shift the boundaries of what we can build, a step-change on the order of the shift from pre‑scientific craft to modernity.

Highlights

2025

Actinide is founded by Robert Mendelsohn and Eric Olszewski

2025

Participated in Discipulus Cohort #1

2026

Seed led by Onto

2026

Actinide begins commercial isotope production

This is humanity's grand unsolved problem. It's legitimately the next era of materials. We are supposed to be in the Atomic Age, and we're not. Isotope engineering is a sort of thing that should have happened many decades ago, and we're tardy to it.

Robert Mendelsohn

Co-founder, Actinide

News & Media

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Stage

Seed

Focus

Matter

Energy