A process for preparing polyoxymethylene dimethyl ethers from methanol is disclosed. For example, the process comprises contacting methanol with at least one oxidant in the presence of at least one catalyst wherein the at least one catalyst comprises at least one Group VIB metal component, such as in an amount of from about 0.5 to about 50 wt % (in terms of metal oxide) and at least one Group VIII metal component, such as in an amount of from about 0.2 to about 20 wt % (in terms of metal oxide), and at least one molecular sieve having acidic catalytic activity, such as in an amount of from about 40 to about 95 wt %, based on the total weight of the at least one catalyst for a time sufficient to obtain polyoxymethylene dimethyl ethers.