<p>Over the years, metal oxide semiconductor nanoparticles (NPs) have been thoroughly studied for their synthesis and utilized for various purposes. Although some reports claim to have synthesized such NPs at low temperatures, none of the reported synthesis methods involves processing at temperatures below 10&#xa0;°C. For the first time, we report ice bath-assisted low-temperature chemical synthesis of 4 metal oxide nanoparticles (MONs), where the temperature was maintained from 0 to 5&#xa0;°C throughout the process. ZnO, TiO₂, CeO₂, and CuO NPs were synthesized following the precipitation method. The XRD results unveil the polycrystalline nature of the synthesized material for the respective crystal phase, and no trace of the impurity phase. The EDS analysis confirmed the presence of respective metals alongside oxygen with good stoichiometry, and also the purity of the prepared materials. The transmission electron micrographs reveal varied morphology (spherical, distorted ellipsoid) with fine particle size (&lt; 30&#xa0;nm) for all the synthesized NPs. The optical studies estimate the wide-band gap (&gt; 2.5&#xa0;eV) of all the MONs, while the luminescence spectra provide information regarding the emission properties in correlation to the exciton recombination. The photocatalytic tests were conducted under direct sunlight to simulate real-world conditions for textile effluents. The experiment against RhB dye insinuates a sublime photocatalytic demeanor by TiO₂ NPs (~ 100% degradation), followed by ZnO NPs. Accounting for a higher band gap and higher recombination rate, CeO₂ and CuO NPs exhibit undesirable photocatalytic performance. Photolysis experiments were also conducted to estimate the self-degradation of model pollutants under sunlight. The competence of TiO₂ was further reconnoitered to check the influence of pollutant concentration on the degradation.</p> Graphical Abstract <p></p>