If it's not wicker....a brush on paint will do a better job...but if they were cheap chairs and you just want to spruce them up....get the best gloss white they have and buy 2 cans and give it go.
But unless you have a "box" to spray in, you will make a mess somewhere! Just don't make your grass white before a party....ask me how I know that!!
Linda c

I have done a few small jobs with spray paint and found it is not as easy as it looks.

I hate spray paint. I got a wooden rocker at Goodwill that just needed a little freshening, no sanding or stripping, I just used a good brush and the SW Duration paint that I used on my exterior trim. Not perfect, but good enough. And that's coming from a perfectionist!

Be sure you buy some spray primer (white) and use that lightly over the whole chair before you apply the paint. You want to make sure you get the primer on the worn/wood exposed areas. Using it will make a huge difference in the longevity of the paint.
The key to getting a nice finish is to follow the directions and spray on 'light' coats. If you get a drip, have a quality paint brush handy to feather it out.

Painting with a brush is going to take a lot of time, especially if your chair have slats, so I'd try the spray if you want it done by the weekend. Ideally, you'll want the paint to cure at least 2 days before the chairs are used.
Since you have two chairs to do, be sure to get the brand that has the ergonomic finger grip.....I believe it's Rustoleum. It's easier, faster, and your finger won't cramp after the first 3 minutes!

It may work, but I would definitely roughen up the chairs before applying any type of paint. Rustoleum is a good brand. You may want to use an acrylic spray to seal it once you've painted.

Thanks for the above responses. I am armed and ready to give it a go tomorrow morning.....and will be sure not to set up on the lawn (nod to lindac)!

I spray painted a metal table once and it looked fine. You just need to be sure to use long even strokes and put on several thin coats in layers, rather than one thick coat that can drip. I find it is easier than painting with a brush.

We will need some pics, please.