Campbell Robb, director general of the office, has hired Vanessa Potter, former director of policy at the Big Lottery Fund, to conduct a review of the office's staff and work.
The review is one of Robb's first major actions since taking up the post last October.
The OTS declined to comment on the contents of the review.
It is also set to monitor the Fundraising Standards Board's impact on public trust as part of a five-year study to measure the effectiveness of the Charities Act.
It will question 3,000 people about their trust and confidence in charities through the Office for National Statistic's Omnibus survey. Results will be published in April.