Growth in passenger numbers, however, slowed from 13.7 pct in July, it said.
The airline's average passenger load factor in August stood at 81.8 pct, it said in a statement, adding that the airline's performance in the month was slightly below its expectations.
"The August figures were a little disappointing as we did not manage to break any summer passenger records, said Ian Shiu, airline manager for sales and distribution.
"August is a peak month for summer leisure travel, yet year-on-year passenger growth dipped below a corresponding 11.9 pct increase in capacity and did not beat it, as it has for most of the year," the statement said.
In the same month, Cathay carried 94,552 tons of cargo, up 22.1 pct over the same month last year.The average cargo load factor in the month was 64.3 pct, the company said.
Cathay said August's cargo figures were also below its expectations as high transhipment tonnage growth masked a weaker performance in exports from southern China.
"Rates are under pressure as a result of excess capacity being deployed into China and Hong Kong, and we are concerned about the impact of high fuel prices on demand," said Ron Mathison, director of Cathay's cargo operations.
Despite the slower growth in August, however, the airline is still optimistic about its outlook.
"Still the outlook for bookings in September is good," Shiu added.
At 2:09 pm, Cathay was up 0.05 hkd or 0.36 pct at 13.95.
Want more analysis like this? CAPA Membership gives you access to all news and analysis on the site, along with access to many areas of our comprehensive databases and toolsets.
Find out more and take a free trial.