The CPI climbed 2.38% in October from a year earlier, compared with a forecast for a rise of 1.91% in a Reuters poll and against September's 1.68% increase.
The CPI is likely to increase later this year, though not sharply, due in part to government measures to support oil prices, senior ministry official Ronnarong Phoolpipat told a news conference.
It is projected to rise by 2.43% in the fourth quarter year-on-year, he said.
For 2021, the ministry is maintaining its forecast for headline inflation of 0.8% to 1.2%, he added.
In October, the core CPI index was up 0.21% from a year earlier, compared with a forecast for a 0.30% rise.
In the January-October period, the headline CPI rose 0.99% from a year earlier, with the core rate up 0.23%.
(Reporting by Orathai Sriring, Kitiphong Thaichareon and Satawasin Staporncharnchai; Editing by Martin Petty)