Here are some of the most commonly used ukulele tonewoods

Koa » This dense tropical wood that's native to Hawaii was the traditional wood of choice for ukuleles, and is still among the most popular for its beautiful grain patterns, wide range of colors, and balanced tone.
Acacia, which is botanically related to koa, has similar properties.

Mahogany » Since it includes many varieties grown in various regions of the world, it's hard to generalize about its tone, but mahogany generally imparts a darker, warmer tonality. Mahogany is often used for ukulele necks.

Spruce » With the recent popularity of ukuleles, many guitar builders have begun making them using the same woods used in guitar tops. A top choice of guitar makers, spruce's dense grain produces loud and bright tones with lots of "zing."

Cedar » Being softer than spruce, it offers tones that are much more mellow and round. It's a good choice for bringing out the lower notes produced by tenor and baritone ukuleles. Western red cedar is one of the most popular varieties.

Rosewood » Commonly used on ukulele fretboards, this dense wood can also be used for ukulele bodies. Aside from its hardness, rosewood's rich coloration and figuring can add to the ukulele's visual appeal.

Maple » Another wood often used in guitars, it has a dense grain that is sometimes attractively figured. Its hardness lends itself to ukulele bridges and fretboards.

Today, you'll find ukuleles made from dozens of wood varieties including ovangkol, cocobolo, nato, beech, myrtle, cherry, bubinga, mango, pau ferro, sapele, wenge, and many more.