With Priceline’s acquisition of Kayak expected to close May 21, Priceline will have a new weapon in its arsenal, but CEO Jeffery Boyd vowed today that Priceline won’t do anything to bias Kayak’s search results.

Appearing on CNBC today, Boyd said that Priceline won’t do anything to upset the level playing field that exists among Kayak’s advertisers.

Boyd said Priceline will take no actions to “compromise the integrity of a great marketplace.”

That may come as good news to Kayak’s advertisers as Priceline, and subsidiaries Booking.com, rentalcars.com and Agoda, already accounted for 10% of Kayak’s revenue in 2012, second only to Expedia Inc.’s 26% contribution to Kayak’s total revenue.

You can expect that mix to change, however, as Priceline and Expedia jockey over their new travel metasearch holdings in Kayak and Germany’s Trivago, respectively.

Now that TripAdvisor has launched hotel metasearch, the maneuverings among major players will be fascinating to watch.

In other matters, Boyd provided further detail on Booking.com’s U.S. offline advertising campaign, which he characterized as an “experiment.”

Asked why Booking.com would make that investment in the U.S., rather than in an emerging market, Boyd said other OTAs already have a voice in offline advertising in the U.S., and it was important to ensure that Booking.com also has a voice, too, so it doesn’t lose customers.

Boyd added that the U.S. is a large market, that Booking.com can reach a lot of people in the U.S., and because it is relatively new to the U.S., Booking.com has plenty of room to grow.

And, Booking.com is indeed likely to grow in the U.S., as a complement to Priceline.com.

Photo Credit: Priceline CEO Jeff Boyd's mug, on stage at PhocusWright 2011 conference. PhoCusWright / Flickr.com