<p>In this work a simple methodology was developed by means of a citric acid-assisted sol-gel process for the synthesis of mixed oxides Ln_2/3Cu₃Ti₄O₁₂ (Ln = La, Pr, Nd, Gd, Er, Tm, and Yb) and Ce_1/2Cu₃Ti₄O₁₂. To obtain Ce_1/2Cu₃Ti₄O₁₂, a study was performed by X-ray diffraction (XRD), UV-Vis spectroscopy and infrared spectroscopy, monitoring the evolution of both the surface chemical groups, forbidden gap width energy, as well as the crystalline phases present in the material as a function of the calcination temperature. The optimal temperature (which allows a high phase purity ~90%) of calcination to obtain the double perovskites was found to be 1070 °C. The other samples of Ln_2/3Cu₃Ti₄O₁₂ (Ln = La, Pr, Nd, Gd, Er, Tm, and Yb) were treated at this temperature obtaining mainly a type A double perovskite structure, as evidenced by XRD and high-resolution transmission electron microscopy (HRTEM). As a complement to the XRD, Raman spectroscopy was used to explore the characteristic vibrational modes of type-A double perovskites, with the spectra being assigned via density functional theory (DFT) calculations. Finally, this work proposes a commercial, scalable, and economic sol-gel-based methodology, which is extremely useful in the synthesis of complex ceramic compounds constituted by multiple metallic species.</p> Graphical Abstract <p></p>