Tetrahexyldecyl ascorbate is a form of vitamin C that's been modified to be more lipid soluble. This modification allows it to better penetrate the skin. The problem with most topical forms of vitamin C is they're water soluble and can't make it through the lipid-rich skin barrier to reach the dermis of skin where they could have maximal benefits. Tetrahexyldecyl ascorbate is able to successfully penetrate the epidermis and move to the layer underneath called the dermis. It's in the dermis that collagen, a protein that gives skin its youthful firmness and ability to resist wrinkles

 

Tetrahexyldecyl Ascorbate is a stable, oil-soluble form of Vitamin C, used in cosmetics, personal care products and anti-aging products because of its ability to increase collagen levels, reduce melanin production, brighten skin, and repair the effects of UV exposure and other environmental damage. It is also considered to be more potent than L-asorbic acid and other Vitamin C compounds, and has a higher rate of penetration (because it is lipid soluble, like human skin) than other derivatives; it also has a higher rate of conversion to vitamin C within the dermis.