Abstract: The invention relates to a method of preparing acrylic acid by selective oxidation of propane in a circulating fluidised bed or in a fluidised bed in the presence of a catalyst having structure Mo1VaXbZcSidOx(I), wherein X represents tellurium or antimony and Z represents niobium or tantalum, and in which: —a is between 0.006 and 1, inclusive; —b is between 0.006 and 1, inclusive; —c is between 0.006 and 1, inclusive; d is between 0 and 3.5, inclusive; and x is the amount of oxygen bound to the other elements and depends on the oxidation states thereof, which is performed under partial propane conversion conditions and without the introduction of water vapour into the initial gas mixture used to supply the reaction.