A novel cleavable poly(ethylene glycol) (PEG) tether, with a pH-sensitive labile linkage at one terminal and a functional group capable for selective conjugation with a particular group available on the drug molecule at the other terminal, was synthesized and evaluated to contribute the growing demand for polymeric drug delivery applications. Performance of this PEG tether was evaluated using a model drug molecule and hydrolysis using trifluoroacetic acid (TFA) resulted in nearly 50% release of the model drug, while moderate buffers resulted in up to 20% release at 20°C.