Is AOS a sulfate?

No — AOS is a sulfonate, not a sulfate.

The difference is in the chemical bond. In SLS and SLES, the sulfur connects to the carbon chain through oxygen (a C–O–S sulfate ester bond). In AOS, the sulfur is bonded directly to carbon (a C–S sulfonate bond). That small structural difference has practical consequences:

• Better hydrolysis resistance — AOS stays stable in acidic and alkaline systems where sulfate esters can slowly break down.
• Different labeling position — because AOS is chemically not a sulfate ester, some brands use it in "sulfate-free" positioned products. Whether that claim is acceptable depends on the rules and enforcement practice of your destination market, so confirm wording with your regulatory advisor before printing it on a label.

In formulation terms, AOS still behaves as a strong anionic surfactant with excellent foam and detergency. Browse our AOS product range or ask our team how it fits your formula.