Theologically conservative, but engaged in confronting poverty and other social problems, the Franciscan archbishop of San Paulo is considered one of the strongest Latin American candidates.
He agrees with the Vatican's position that consideration for the poor should be dictated by the Gospel and not political ideologies.
When he became a bishop, he opened his churches to workers staging an illegal strike.
One of those workers was Brazil's now-president Luiz Inacio Lula da Silva.
Hummes has taken a strict line on homosexual rights, abortion, celibacy and condom use.
He has also said Catholics are not doing enough to broaden their evangelical efforts.
Hummes is cautious, open to debate with a good sense of humour. But his age may be a problem, since he is only 60, and may be considered too young.