Abstract: The present invention provides a simple, 1-step process for preparing a N-(aryl or heteroaryl)-hydroxyurea comprising reacting the corresponding alcohol, ester or ether with hydroxyurea and acid. This reaction is particularly useful for preparing a benzo[b]thienyl substituted N-hydroxyurea of formula: ##STR1## from compound 1: ##STR2## by reacting compound 1 with hydroxyurea and acid. R.sup.1 is selected from the group consisting of hydrogen, 1-6 carbon alkyl, 1-6 carbon alkoxy, and halogen; R.sup.2 is an 1-4 carbon alkyl; and R.sup.3 is selected from the group consisting of hydrogen, acyl, methyl, ethyl and mixtures thereof. Additional steps to isolate the pure bulk product follow.