It has 11–14 deeply notched ribs divided into humps.

The strong, curved spines are yellowish-brown with darker tips, aging to gray.

The flowers are pink to white, sometimes with a darker throat, and measure up to 8 cm in length and diameter.

[3] First described as Echinocactus mostii by Max Gürke in 1906, the species was renamed by Nathaniel Lord Britton and Joseph Nelson Rose in 1918.

Its name honors Argentine plant collector Carlos Most.