In the present work a comparison between two different working solutions in the H2O2 catalytic direct synthesis (CDS) was studied in a continuous reactor. The two working solutions (i.e. water and methanol) were chosen due to their large use in the catalytic direct synthesis. Both the working solutions have advantages and drawbacks: it is well known that methanol is mainly used due to the possibility of higher H-2 and O-2 solubilization compared to water, while water is the "greenest" solvent for excellence. Different parameters such as temperature, gas now rate and catalyst amount were studied in order to identify the major differences between water and methanol. A study to compare the gases solubility in our conditions in water and methanol was performed in order to understand how gas solubility can affect the reaction. Gas solubility was found to be 10 times higher in methanol compared to water. Consequently the consumption of the reagents was faster in methanol compared to water Unexpectedly, the final concentration of H2O2 was comparable between water and methanol working solutions at the different operations conditions studied. This indicated that the transport phenomena are important to fine tune the reaction path. The maximum H2O2 was around 2.3 wt%. (C) 2014 Elsevier Ltd. All rights reserved.