Abstract: This study involved formulating nutritionally suitable complementary food mixtures with locally available raw materials. Maize or sorghum was mixed with cowpea, soaked at 25 °C for 72 h, wet-milled and sieved. The sediment was sun dried, milled for analyses. Proximate, functional properties and amino acid were determined in co-fermented maize/cowpea and sorghum/cowpea. Sorghum/cowpea had higher water absorption capacity, (235%) than maize/cowpea (103%) sorghum/cowpea and a lower value of oil absorption capacity (47.9%) than, maize/cowpea of (67.6%). Oil absorption capacity of (14.7%) in sorghum/cowpea was higher than (9.6%) in maize/cowpea. The higher foaming capacity of maize/cowpea (40.0%) than that of sorghum/cowpea of 20.0% might be due to soluble proteins and higher emulsion capacity of maize/cowpea might make it a better flavour retainer and enhanced mouth-feel. Values of foaming stability, least gelation capacity and bulk density (loose and packed) were comparable. Sorghum/cowpea had higher contents of lysine, histidine, arginine, aspartic acid, threonine, serine, alanine, glutamic acid, proline, glycine, cystine, valine, isoleucine, leucine, tyrosine, phenylalanine, total amino acids, total sulphur amino acid, ratio of total essential amino acids/aromatic amino acids but lower values of methionine and total essential amino acids. Thus co-fermented sorghum/cowpea is of better protein quality than maize/cowpea.