We present the results of experimental investigations on bandgap bowin
g and spontaneous ordering in MOVPE grown ZnSexTe1-x. The bowing param
eter of b = 1.40 +/- 0.05eV found from different optical measurements
on our epilayers is slightly larger than values found earlier from bul
k material, indicating the possibility of spontaneous ordering in our
samples. Ab-initio calculations for Zn2SeTe in the ordered CuAu- and C
uPt-structures lean support to this possibility. In fact X-ray measure
ments performed on our samples with x = 0.39 and x = 0.54 show peaks,
forbidden in the zincblende structure, which give evidence for spontan
eous ordering in the CuPt structure.