Selective production of benzaldehyde, an industrially relevant precursor material, by oxidation of organic pollutant toluene, in a mild environment-friendly green condition, is still a challenging task. Herein, MnWO4 is demonstrated as an efficient catalyst to prepare benzaldehyde by direct oxidation of toluene in presence of H2O2 as oxidant at 80 oC via C-H activation, with excellent conversion rate and high selectivity. MnWO4 nanobars (NBs) are synthesized in a single-step facile hydrothermal process and its catalytic performance for toluene oxidation is compared with MnWO4 nanoflakes (NFs) obtained by a precipitation method. Under an optimal condition, 59.5% of toluene conversion with 90% selectivity towards benzaldehyde has been achieved by using MnWO4 NBs which is higher than that of NFs catalyst. This is due to a larger number of positively charged sites and an abundance of acidic sites on the NB as compared to the NF. Different reaction parameters such as reaction time, oxidant concentration, catalyst concentration, and reaction temperature are varied systematically to obtain the optimal reaction condition. The stability, recyclability, and leach test show no loss of catalytic activity and/or degradation of catalyst. This proves the pure heterogeneity and recyclability of the catalyst, the important criteria for industrial application.