Supranee Chatraratanavong, director of the centre in the Office of the Prime Minister's Permanent Secretary, said 45,000 complaints were filed between May 2 and Aug 8, double the amount received in the two months before the takeover.
Most the complaints were lodged through a telephone hotline, with others taken through the centre's website, its PO Box 1111 mailing address or in person at Government House.
The lion's share of complaints concerned social-welfare issues such as drugs, loan sharks, gambling and electricity woes.
Other types of beefs included accusations against government officials, political and administrative issues, legal problems and complaints about natural resources and the environment.
Mrs Supranee said she believes the increase is due to a feeling among the public that the NCPO, which has taken on a myriad of issues since ousting the government, can do something to help them.