We establish a v₁-periodicity theorem in Ext over the C-motivic Steenrod algebra. The element h₁ of Ext, which detects the homotopy class η in the motivic Adams spectral sequence, is non-nilpotent and therefore generates h₁-towers. Our result is that, apart from these h₁-towers, v₁-periodicity operators give isomorphisms in a range near the top of the Adams chart. This result generalizes well-known classical behavior.

The author would like to thank Bertrand Guillou for useful instructions and helpful discussions. The author also benefited from discussions with J.D. Quigley, Eva Belmont, and Prasit Bhattacharya and appreciates their assistance. The author thanks the referee for providing detailed comments that helped to improve the exposition of the article.