Low morale, made worse by funding problems and difficulties caused by culturally diverse workforces, had led to high staff turnover and poor performance, a range of NGOs told researchers, who spoke to 28 organisations in Honduras, India, Kenya and Pakistan.
People In Aid concluded that NGOs should find better ways of engaging staff and volunteers. Recommendations included giving employees more opportunity to discuss and develop their careers and participate in decision-making.
"Motivating staff and volunteers is a major challenge for NGOs working in the south," said Jonathan Potter, executive director of People In Aid.
"This research will be of practical assistance to southern NGOs and international NGOs with operations in the south."
Amicus is urging charities to end the long hours culture in the sector.
A survey of 350 charity workers by the trade union found that 56 per cent of respondents worked more than 36 hours a week, a third felt pressured to work long hours and 60 per cent struggled to balance work with other activities.