  The Tevatron proton-antiproton collider at Fermilab with its centre of mass
energy of 1.96 TeV allows for pair production of top quarks and the study of
top quark decay properties. This report reflects the current status of
measurements of the W boson helicity in top quark decays and the ratio of top
quark branching fractions as well as searches for neutral current top quark
decays and pair production of fourth generation t' quarks, performed by the D0
Collaboration utilising datasets of up to 5.4/fb.
