Hyatt Hotels is guaranteeing that hotel rates published on its Hyatt.com Web site will be the lowest published rate available.

Hyatt’s new Best Rate Guarantee promises that if a consumer finds a lower rate for a Hyatt guest room on a third-party web site, such as Expedia or Orbitz, Hyatt will give that person a 20 percent discount off the third-party rate. To get the discount, the consumer must call (888) 96-HYATT so that a representative can verify the lower third-party rate.

The guarantee does not apply to certain types of Web sites, such as those offering package deals that include hotel room rate as well as airfare and car rental. It does not apply to sites like Priceline.com, where the consumer doesn’t know the hotel brand at the time of bidding. And it does not apply to negotiated group rates or qualified discount rates, such as AAA.