To obtain a cold-setting composition having excellent workability by using a hydrolyzable sily-modified product of a (meth)allyl-terminated polyoxyalkylene ether having a specified polydispersity index.

An allyl alcohol/alkylene oxide adduct is mixed with Ce(OH)3 catalyst and polymerized while adding an alkylene oxide to the mixture at about 80-110°C to prepare a polyoxyalkylene mono(meth)allyl ether having a number-average molecular weight of 3,000 or above. Next, an aldehyde and an acid catalyst are added to the reaction mixture and reacted in a vacuum to effect bimolecular bonding. The formed (meth)allyl-terminated polyoxyalkylene ether is reacted with a silicon hydride compound (e.g. dimethoxysilane) at about 150°C or below in the presence of a platinum catalyst (e.g. chloroplatinic acid) to obtain a hydrolyzable silyl-modified product having a polydispersity index of 2.0 or below. This product is mixed with about 0-10wt.% silanol condensation catalyst (e.g. tin octoate), about 5-200wt.% filler, a plasticizer, etc., to obtain a cold-setting composition.