Abstract: The present invention provides an apparatus and method for inducing hydrophobicity in selected barrels of multi-barreled microelectrodes made from glass microcapillaries in a consistent and simultaneous fashion. The apparatus for producing hydrophobicity under substantially identical conditions includes a housing defining a gas-tight chamber and made of a material substantially inert in the presence of a volatile hydrophobicity-inducing solution. The housing includes a port in communication with the chamber for injection of a volatile hydrophobicity-inducing solution into the chamber and the housing also includes a plurality of ports in communication with the chamber for receiving a single or multibarreled microelectrode therein, each of the ports having a seal for forming a gas-tight seal around each microcapillary in the port.