Polyelectrolyte ultra-thin multilayers were prepared on single crystal silicon by alternative deposition of acid red 18 as anion and poly(ethylenimine) and poly(allylamine hydrochloride) as polycations．The films were characterized by means of ultra violet-visible light absorption spectrometry and contact angle measurement．The thickness of the ultra-thin self-assembled films was determined with an ellipsometric thickness tester．The friction and wear behavior of the ultra-thin films under one-way dry sliding against AISI-52100 steel was examined on a DF-PM friction coefficient measurement apparatus in a ball-on-block configuration．As the results

the deposition of the ultra-thin films on the single crystal Si leads to alternate variation in the contact angles of distilled water thereon．Both the two kind of ultra-thin films show good friction-reducing and antiwear behavior in sliding against the steel at a relatively low load

while the tribological behavior of the films is dependent on the bilayer numbers of the films．The ultra-thin film of eight bilayers made from poly(ethylenimine) and acid red 18 records a low friction coefficient in sliding against the steel even above a sliding cycle of 2000．Thus it might be a potential candidate as the friction-reducing and wear-resistant ultra-thin film material for some micro devices．