Some solid solutions have been strongly utilized over the years as good materials for the synthesis of electrocatalysts and photoctalysts. Sometimes, they are used as supports in order to improve electrocatalytic and photocatalytic properties. We show various achievements of solid solutions as good electrocatalysts, and also, good electrocatalysts support materials in oxygen reduction reaction (ORR), hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Also, we demonstrate various works utilizing solid solutions as good photocatalysts, and good photocatalysts support materials in overall water splitting and carbon dioxide reduction. In all these reports, solid solutions proved to posses the necessary properties needed of any material as electrocatalysts and photocatalysts. In many cases, their use as catalysts supports recorded great improvements. X-ray photoelectron spectroscopy (XPS) was largely used to confirm the chemical environment of the results obtained, together with X-ray diffraction (XRD). In the electrochemical methods, cyclic voltammograms (CVA), chronoamperometry and rotating disk electrode (RDE), were also carried out. Linear sweep voltametry (LSV) curve was carried out in some cases to measure the current at a working electrode, and tables were shown for clear explanation. In addition, a photoluminescence spectrum (PL) was used to probe the electronic structure of the various solid solutions.