The conservative Canadian leader was to meet with the left-leaning leader of Brazil, President Dilma Rousseff, Monday, The Globe and Mail reported.
Harper also is to stop in Colombia, Cost Rica and Honduras on his trade trip.
Postmedia News reported Harper will attempt to bolster Canada's sometimes tepid relationship with Brazil. He is expected to outline ways to strengthen trade ties between the two countries during a speech to political leaders, businessmen and educators Tuesday in Sao Paulo, the news agency said.
"Of any major emerging economies, Brazil presents Canada with the most opportunity for export, as well as for companies that are looking at doing business in that country," Jayson Myers, president of the Canadian Manufacturers and Exporters, told Postmedia News.
"Brazil has a very strong economy and I think Canada does not bring a lot of that political baggage that businesses from other countries do. It's a market that businesses now are beginning to find is a very lucrative opportunity for them."