Positron-emitting fluoridated organo-fluoroborates comprising at least one 18F atom and precursors thereto, for use in position-emission tomography (PET) scanning and methods for their production are provided. The compounds have the general formula ( Y1 )n( Y2)B( A) (I)； wherein B is boron, A is a linear or branched alkyl, alkenyl, alkynyl or non-aromatic cycloalkyl group, any of which may include a heteroatom； A is joined to B through a carbon atom； each Y1 and Y2 are selected from the group consisting of a non-interfering group with regard to the fluoridation of B, a 18F or a 19F, wherein at least one of ( Y1)n and Y2 is 18F； and provided that A is selected such that the pKa of Ha of an acid of the formula HaOC(O)A is less than or equal to about 2.8.
