Isononyl Isononanoate is the ester of isononanoic acid and isononanol alcohol.

It is a highly branched low molecular weight, dry and silky ester that exhibits unique characteristics including extremely low freeze point, low viscosity, good penetrating power, excellent solubility and compatibility in a variety of ingredients such as esters, volatile silicones, mineral and vegetable oils. It acts as a replacement for volatile silicones in antiperspirants where it reduces tackiness and prevents clogging in aerosols and as a resin plasticizer in hair sprays.

In particular is skincare products, it gives them a distinctive velvety feel.