A room temperature curable organopolysiloxane composition comprising a diorganopolysiloxane having a hydroxyl group or alkoxy groups, a filler, a particular alkoxysilane, an organosilicon compound having a particular guanidinyl group, and an organic tin compound, and further comprising an organosilicon compound having at least one group represented by the general formula: ##STR1## where R.sup.4 is a substituted or unsubstituted monovalent hydrocarbon group, or a substituted or unsubstituted phenyl group, R.sup.5 and R.sup.6 are each a hydrogen atom, methyl or ethyl group, and n is an integer of 0, 1 or 2. By virtue of the last component, the composition exhibits markedly good storage stability.