Since you didn't say much about where he lived or where he died, I took a stab at this and found that he died in Sparks, Doniphan, Kansas.
John S Wilcox and Mary Elizabeth Barnes married in Waukeska Wisconsin on Sept 27, 1853. Then I found that he was actually born in Belbour, England to John and Mary Wilcox. John Wilcox was born on or about 1789 England and Mary was born about 1791 England.
I found a 1850 Census England
John Wilcox - age 61 Born England - Mary Wilcox age 59 ----Maria Wilcox - age 21 - John Wilcox - age 25 --- William C Rowe - age 8 - Walter Searle -age 30, --Anna Searle -Age 27 My guess is that Anna Searle could be Anna Wilcox and they just could be living with the parents. I don't know for sure and it could also be that John Wilcox could have left for the United States about 1851or 1852 then arrived in Wisconsin to meet and marry Mary Elizabeth Barnes.
This is all that I could find, but maybe if you need anymore help please let me know. Thanks Nancy