Nanosuspensions are proposed for use in improving the thermal efficiency of different thermal systems; including solar thermal power plants. Because of their excellent and unique thermo optical properties, which are the basis of thermal transfer phenomena, they are used as working fluids in solar thermal collectors for photothermal energy conversion. However, particle agglomeration in nanosuspensions remains one of the most important challenges faced in terms of their usage. The purpose of this study is to investigate the particle agglomeration behavior of water based Al2O3 and TiO2 individual and hybrid nanosuspensions and observe their effects on spectral radiative properties. By carrying out number of experiments, the effects of similar and dissimilar particle agglomerations on radiative properties are clarified. The results show that pH have significant effect on the particle agglomeration which in turn affects the optical and radiative properties involving individual and hybrid nanosuspensions. Particle agglomerates (similar and dissimilar) plays an important role when specific radiative properties are required for specific applications. Different regimes of the dependent/independent scattering can be obtained from the effect of similar and dissimilar particle agglomerates of a particular nanosuspension.