It can be done, but for stability i would get a john boat or a canoe.
The kayak can be used simply for transportation but unless you get a huge one, it won't carry too many decoys. If you do get a kayak , get a life preserver for you and your gun.

Get the jon boat. First off, it is safer and more stable. Second, you can get more gear like decoys. Third, you can get blinds that mount to the side of the boat. That and good luck trying to fit 3 people into a kayak. I hunt out of a jon boat, and when i need to get somewhere special, i use a canoe. As for being old enough, I am sure you are, but check your state regs.

I’ve used a kayak to get in to duck hunting areas many times. Works fine, but you need a large enough kayak to carry decoys, etc. When I was young we had a big two-person Klepper kayak. We also did a lot of jump shooting on rivers – two guys trading off – one paddling in the stern and one in the bow with the shotgun. We had lots of fun and bagged plenty of mallards, teal and wood ducks that way. But like others have said, most kayaks aren't really designed for that kind of use, and a canoe might be a better choice.

not a kyak but as a kid I used to float rivers in a canoe with my family hunting ducks and canadian geese. Worked well until the river would freeze over in the winter and you make too much noise busting ice.

Normally it allows you to float silently, in the bends and backwaters we would find the ducks and by the time the spook and take off, they were in range

I wouldn't use a kayak for all the above reasons. Also I've had good luck with a john boat. But keep in mind a layout boat looks somewhat like a kayak and I've seen guys using them murder mallards and sprigs. Just keep in mind most are one man only and carry only 1 0r 2 doz dekes which should be plenty. To a duck it probably looks like a floating log. Layouts are usually camouflage painted and the kayaks I have seen are usually brightly colored. Maybe what you meant was a layout.

It is now illegal to hunt from a mobile boat. However long ago, I thought it was legal (I hope) and thought my little kayak would position me wonderfully for low passing Mallards on a tough to reach little pond. Of course I never thought about the recoil of my 3 inch 12 gauge with hot and heavy hand loads. I quietly paddled to a nice concealed spot near an open patch of water... perfect! I couldn't wait for the first flock and thought I'd discovered a gold mine!

A nice flock of mallards approached low to the water from my starboard side. This just looked to good to be true. I easily drew a bead on the leading drake and fired my first shot. I never even saw whether I hit him or not! The kayak flipped over so fast I took me a second to realize what had happened. Somehow it seemed like instead of a flock of ducks, I was now aiming at nothing but water as I dangled upside down beneath my overturned kayak in freezing water.

I thought for sure I was going to die of hypothermia on the return cruise. It was back to the drawing board for me and that is the last time I ever shot from a kayak. Obviously, I'd recommend a Jon boat too.