Hydrox is the brand name for a creme-filled chocolate sandwich cookie which debuted in 1908 and was manufactured by Sunshine Biscuits. Its name was formed from the atomic elements which make up pure water: hydrogen and oxygen. Some accounts report the Oreo—introduced later, in 1912—was inspired by the Hydrox, yet Hydrox suffered from the misimpression it was a knockoff. Compared to the Oreo, the Hydrox had a "tangy, less-sweet filling" and a crunchier cookie that stood up better in milk.
On the occasion of the cookie's 100th anniversary, Kellogg's is again distributing Hydrox under the Sunshine label, with the first batches shipped in late August 2008. Hydrox aficionados bombarded Kellogg's with thousands of phone calls and an on-line petition asking that production resume. The cookies will be available nationally for a limited time, but good sales might lead to continued production. The recipe will be slightly altered from the original; trans-fats are removed.
The Carvel ice-cream franchise still sells ice-cream goods manufactured with "Hydrox" cookie crumbs. Carvel uses the cookies' all-kosher status as a selling point, so these cookies are presumably made with the same recipe as the original. The cookies are not specifically mentioned by name on the Carvel website, but they are identified as hydrox (lower-case 'h') on the in-store posters.
Lupe Fiasco made reference to Hydrox in the song Everybody Nose (Remix). In an episode of the animated television series Family Guy, an advertisement announces a doctor performing Lasik eye surgery for $12 at the Hydrox Arena.