The Sb adsorption process on the Si(111)-In(4 x 1) surface phase was studied in the temperature range 200-400 degreesC. The formation of a Si(111)-InSb (2 x 2) structure was observed between 0.5 and 0.7 ML of Sb. This reconstruction decomposes when the Sb coverage approaches 1 ML and Sb atoms rearrange to (root3 x root3) and (2 x 1) reconstructions; released In atoms agglomerate into islands of irregular shapes. During the phase transition process from InSb(2 x 2) to Sb(root3 x root3) (theta(Sb) > 0.7 ML), we observed the formation of a metastable (4 x 2) structure. Possible atomic arrangements of the InSb(2 x 2) and metastable (4 x 2) phases were discussed. (C) 2002 Elsevier Science B.V. All rights reserved.