greatly exceeding twice the diameter of the starting urea particle to obtain acceptable coating adhesion actual weights of the added metal oxide will depend upon the density of the metal oxide powders used and can range up to about 40 percent by weight of the starting urea particle if an additional outer coating of sulfur is desired the sulfur content of the finished product will be between about 5 percent and about 20 percent by weight the metal oxide coated particles of this invention have been found to possess a very high resistance to caking during storage resistance to increased moisture content during storage in high humidity atmospheres can be improved by adding a coating of sulfur to the particles particles of urea which are coated only with metal oxide absorb moisture much the same as uncoated urea but exhibit much less tendency to cake when damp metal oxide coating also usually increases the resistance to crushing of urea particles the invention is further illustrated by the following examples which are illustrative of various aspects of the invention and are not intended as limiting the scope of the invention as defined by the appended claims in the examples all percentages are expressed on a weight basis in an experiment to determine the stoichiometry of metal oxide urea reactions the finely divided compounds are intimately mixed in the proportion of 1 mole metal oxide to slightly more than 2 moles urea the mixture is heated to initiate a reaction and maintained at an elevated temperature below the melting point of urea water which forms during the reaction according to the equations noted supra is determined by measuring weight loss results are as shown in table i table i______________________________________metal heating moles h sub 2 o.