|City||Saint John, New Brunswick|
|Slogan||Saint John's Perfect Music Mix|
|Frequency||100.5 MHz (FM)|
|First air date||1987|
|HAAT||381.5 meters (1,252 ft)|
|Owner||Maritime Broadcasting System|
|Sister stations||CFBC, CJYC-FM|
CIOK-FM, is a Canadian radio station broadcasting at 100.5 FM in Saint John, New Brunswick, owned by the Maritime Broadcasting System. The station currently offers an adult contemporary format branded on-air as K100 "Saint John's Perfect Music Mix". Prior to July 2009, it had an adult contemporary format before changing to contemporary hit radio. As of September 2015, the station moved back to adult contemporary.
K100 was being programmed out of Moncton and in order to cut costs, MBS decided that instead of flipping K100 to a classic hits format they would change the format to a contemporary hit radio format to more effectively compete with rival CHWV-FM. CIOK-FM's switch to contemporary hit radio joined sister station CKCW-FM in Moncton, which moved from top 40 to hot AC by that same time. Nielsen BDS later moved the station to the Canadian hot adult contemporary panel after the flip of this station to top 40. In September 2015, the station returned to adult contermporary.
On December 3, 1986, Mervyn Russell, representing a company to be incorporated received approval from the Canadian Radio-television and Telecommunications Commission (CRTC) to operate a new FM radio station at Saint John. The station began broadcasting in 1987 with Gary Crowell as the GM, and Jim Goldrich returned to K100 from working at CJYQ in Newfoundland. K100's original studios and offices were on 400 Main Street in Place 400. In the mid-1990s, K100 moved their studios and offices to Union Street, where they are still located. In 1997, the station was purchased by Newcap Broadcasting and was re-purchased by MBS Radio in 2005.
K100 was the long-time radio home of Saint John radio personality Bruce Weaver who hosted K100's morning show from 1991 to 2002 and made K100 #1 in the ratings during that time.
K100 announcers along with the announcers of two other MBS stations and support staff continue their strike for a fair deal.
Although the station's reports are not on Mediabase, the station's ads were exactly the same as sister hot adult contemporary station CKCW-FM in Moncton; however, Mediabase now lists the station as of March 2011 for adds on the same Canadian hot AC panel as rival CHWV-FM. As of August 2011, MBS's website identifies CIOK-FM, and sister station CKCW-FM's, formats as being CHR or Contemporary Hit Radio.