The record adult male bobcat weighed 26.8 kilograms which is 59.1 pounds. The source for this information is The bobcat of North America by SP Young. The book was published in 1978 by Lincoln: University of Nebraska Press. This record weight is heavier than the record as found by Google in its search results for the search term in the title.
Google presents information from retrieverman.net. This website says that the heaviest bobcat on record weighed 48.9 pounds. It was shot in 1984 in Marinette County, Wisconsin.
The picture below is the Marinette County bobcat:
Note: I have to record my disgust at the photograph. Such a beautiful cat killed for the fun of it.
The heaviest female bobcat on record from the same source (SP Young) was 15.9 kilograms which is 35.05 pounds.
Heavier in the North
Bobcats in northern latitudes are normally larger than those in the southern areas of their distribution. In Oklahoma the average weight from a small sample of adult males was 8.9 kilograms (19.6 lbs) and for females it was 5.8 kilograms (12.8 lbs). For Northern Minnesota adult males weigh an average of 13.0 kilograms (28.7 lbs) and females 9.2 kilograms (20.3 lbs).