These findings highlight why online travel sites such as Priceline, Expedia and Orbitz are embracing mobile, which accounted for most of the bookings growth during the first half while desktop bookings were up only 2 percent. The opportunity is not limited to the mobile Web, with in-app bookings also driving incremental bookings for travel companies, accounting for 12 percent of mobile conversions in June.

“The most surprising finding was how rapidly mobile has emerged as a key channel in this industry,” said Jason Morse, vice president of mobile product at Criteo.

“Travel ecommerce shopping is generally more involved for the consumer, and it has, historically, been seen as more daunting on mobile – price comparisons and lengthy checkout processes tend to be difficult on small devices,” he said.

“Yet, we are actually seeing mobile demand skyrocket despite the relative lack of mobile-optimized shopping experiences, which highlights just how large the consumer base is for on-the-go travel shopping.”

The report is based on 1,000 travel Web sites globally that Criteo tracks. In the first half of 2014, the company analyzed 300 million bookings and over $150 billion in booking value.

A better value
The findings underscore the significant revenue opportunities mobile is driving for travel companies. In the U.S., 62 percent of mobile air bookings are over $500 in value and 90 percent are worth more than $300.

One of the biggest opportunities is peer-to-peer apartment bookings, where mobile boasts a 34 percent share of bookings.

The overall value of mobile to travel is higher than before, with the value often on par with desktop and even higher in some categories.

On average, consumers spend $600 more on packages booked on iPad compared to those booked via Android.

The value of Android bookings on flights outpaces that of all over mobile devices.

“The big news is that mobile is now an established start-to-finish travel shopping channel,” Mr. Morse said. “While the emergence of mobile as a major ecommerce platform is not new, the rapidly rising popularity of mobile for travel shopping speaks to both the increased quality of the user experience and the huge opportunity now available to marketers.”

Last-minute bookings
The findings underscore the importance of last-minute bookings for mobile users, with the average booking value for air 21 percent higher on mobile than desktop and 13 percent higher for car rentals. These numbers are largely influenced by the fact that last-minute flights typically cost more.

However, in the hotel category, the value of mobile bookings is 30 percent lower, reflecting how last-minute hotel stays tend to be shorter and of lower value.

These findings suggest that travelers are increasingly relying on mobile devices to make bookings in situations where it is too late for online travel sites to reach them with ads on desktop. Therefore, these sites need to adjust their strategies based on how, when and where travelers make their bookings.

Another key takeaway is that the entire online experience, from ads to shopping carts, need to be mobile-optimized to encourage conversions on all devices.

Additionally, mobile advertising provides increasing conversion opportunities for high-value travel products such as packages and last-minute flights.

Growth to continue
The report also uncovers some interesting differences in mobile bookings trends by country. Japan has the highest rate of mobile bookings followed by Australia and then the United States.

The lowest rates – below 10 percent – are in Brazil and Germany.

“As user experience continues to improve, more travel vendors adopt a mobile-first strategy and the global number of smartphone owners keeps growing exponentially, we could eventually see smartphones and tablets accounting for well over 50 percent of bookings around the world,” Mr. Morse said.

“The mobile channel is perfect for a huge segment of shoppers who need to book travel or accommodations at a moment’s notice,” he said. “Once marketers and developers catch up, there’s no limit to how big this market could grow.”

Final Take
Chantal Tode is senior editor on Mobile Commerce Daily, New York