The makeover, being unveiled Monday, is part of an effort to make U.S. bills harder to counterfeit.
The extra color is subtle, similar to the look of the new $20 bill, which went into circulation last fall with a color treatment featuring touches of peach, blue and yellow.
"The new design is more secure than ever before. We believe it will be extremely effective in discouraging counterfeiters," said Treasury Secretary John Snow. "It's also a lovely piece of currency, maintaining the historic look and feel of a greenback while incorporating the elements of other colors that are very important to us in this country: red, white and blue."
The redesigned $50 is the same size and still features Ulysses S. Grant on the front and the U.S. Capitol on the back.
Some of the old anti-counterfeiting features included in the bill's last makeover, in 1997, were expected to be maintained and improved upon.
They include enhancing some existing security steps, such as an embedded security thread that glows when exposed to an ultraviolet light; watermarks visible when held up to light; and color-shifting ink that looks green when viewed straight on and black when viewed at an angle.
Events to take the wrappers off the new $50 notes were taking place in Washington and in Fort Worth, Texas, where the Bureau of Engraving and Printing expanded its existing production facility and built a tour and visitors center. The new center will allow people to view the production of U.S. greenbacks west of the Mississippi River for the first time, the agency said.
"Adding color is a good idea. It kicks it up a notch and makes it more difficult to counterfeit and adds interest to the bill," said Len Glazer, director of Heritage Currency Auctions in Dallas. "Other countries have been doing it for a very long time."
The bureau expects to print 76.8 million new $50s this year. New bills, however, aren't likely to go into circulation and start showing up in cash registers until fall. Old $50s will continue to be accepted and recirculated until they wear out; they average five years in use.
The bureau also plans to add color to the $100 bill, the most knocked-off note outside the United States. It has not been determined when the new $100 will be unveiled. Officials are still considering whether to redesign $5s and $10s. But $1s and $2s will stay the same because they aren't of much interest to counterfeiters.
Over the years, counterfeiters have graduated from offset printing to increasingly sophisticated color copiers, computer scanners, color ink jet printers and publishing-grade software. Trying to stay a step ahead of the counterfeiters is a challenge, experts said.
"Sophisticated counterfeiting is always going to exist. Whenever there is a way to make money illegally some people will grab for it," Glazer said.