Purpose The purpose of this study was to composite maize, a cereal grain with low protein and lysine content, with groundnut a rich source of protein, to improve the nutritional quality of maize–groundnut composite flours and their resultant porridges. Design/methodology/approach Defatted and full fat groundnut flours were used to prepare maize–groundnut composite flours and porridges at the ratio of 100:0, 55:45, 70:30 and 85:15, respectively. They were analyzed for proximate composition, energy value, amino acid and fatty acid profiles. Findings Compositing maize with groundnut significantly (p ≤ 0.05) increased proteins from 10 per cent in maize flour to up to 21 per cent in composite porridge (denoted DFC1). The energy values for composite porridges were 434 Kcal/100 g when compared with 398 Kcal/100 g established for maize porridge alone. Lysine content was three times higher in composite flours than for maize flour, while for composite porridges, lysine was four times higher than in maize porridge. There was an increase of 35 per cent in oleic acid content when maize flour was composited with groundnut flour. Research limitations/implications Further research is required to evaluate the properties of full fat and defatted maize–groundnut porridges and their effects on consumer acceptability. Originality/value It can be concluded that compositing maize with full fat and defatted groundnut has the capability of improving the nutritional quality of cereal-based diets consequently contributing to a significant increase in nutritional security of African populations and those of other developing countries of the world.