Yes. There's absolutely no problem with using a 10 speed chain on a 9 speed road or mountain drivetrain. Indeed, there are a few advantages:
One such chain is the KMC X10SL super lightweight chain. It features a gold coloured Titanium Nitride ("Ti-N") coating that is supposed to make the chain less susceptible to dirt and easier to clean. The chain also has hollow pins and material removed from the side plates to save weight.
Out of the box, the full length chain weighs 246g including joining link. In comparison, the standard KMC 9 speed chain weighs 285g.