Abstract: There is provided an ink jet ink comprising a binder, a colourant, a liquid vehicle and an adhesion promoter, the adhesion promoter being an alkoxysilane polyalkylene-imine containing repeat units of the formula (I): ##STR1## wherein R.sup.5 represents a bond to another nitrogen atom and R.sup.4 represents a bond to another carbon atom or a hydrogen atom; a is from 1 to 8; b is 1 to 8; c is from 1 to 6; at least one of R.sup.1, R.sup.2 and R.sup.3 is a C.sub.1 -C.sub.6 alkoxy group and any of R.sup.1, R.sup.2 and R.sup.3 which are not alkoxy groups are C.sub.1 -C.sub.6 alkyl groups and p is 1 or more, and x is 1-50.