The dynamics of butanethiol and dodecanethiol monolayers adsorbed on Au(lll) studied by ex situ and in situ sequential scanning tunneling microscopy (STM) shows, at room temperature and in the range of seconds, root 3 x root 3 R30 degrees double left right arrow c(4 x 2) transitions. High-resolution STM imaging also shows that these transitions can be explained by a displacement of adsorbed molecules from hollow to bridge sites and vice versa. Transitions from the p(n x 1) superlattice to the root 3 x root 3 R30 degrees lattice were also imaged in real time. These processes appear robe coupled with fluctuations of the hole size of the Au(lll) terrace.