[en] Nano technology presents new opportunities to create better materials and products. Nano materials find wide applications in catalysis, energy production, medicine, environmental remediation, automotive industry, and other sectors of our society. Nano material-containing products are already available globally and include automotive parts, defense application, drug delivery devices, coatings, computers, clothing, cosmetics, sports equipment, and medical devices. This special issue includes emerging advances in the field, with a special emphasis given to nano material synthesis and applications. There is an increasing interest in identifying magnetically separable catalysts for the degradation of wastewater. In this issue, A. Perumal et al. report an investigation of temperature-dependent magnetic properties and photo catalytic activity of CoFe_2O_4-Fe_3O_4 magnetic nano composites (MNCs) synthesized by hydrothermal processes. These MNCs have saturation magnetization of 90 emu/g and coercivity (HC) of 530 Oe. The photo catalytic activity of the MNCs has been examined on the reduction of methyl orange (MO), a colored compound used in dyeing and printing textiles. The MNCs act as an excellent photo catalyst on the degradation of organic contaminants and degrade 93% of MO in 5 hours of UV irradiation. The photo catalytic activity of MNCs is attributed to remarkably high band gap energy and small particle size. Also, the MNCs with reproducible photo catalytic activity are easily separated from water media by applying an external magnetic field and they act as a promising catalyst for the remediation of textile wastewater. Microwaves can play an important role in orchestrating nano materials for a wide range of technological applications