A novel process for producing homopolymers and interpolymers of olefins which involves contacting an olefin and/or an olefin and at least one or more other olefin(s) under polymerization conditions with at least one Ziegler-Natta catalyst comprising a component comprising at least one transition metal and a co-catalyst comprising at least one organometallic compound and at least one compound comprising at least one carbon-oxygen-carbon linkage (C—O—C) of the formula R1—O(—R2—O)m—R3 in amounts sufficient to reduce the electrostatic charge in the polymerization medium. Also disclosed is a process for reducing electrostatic charge in an olefin polymerization medium.