2 ways you can do that.
1. Better approach is
# strings /PATH/TO/APACHE/modules/mod_jk.so |grep -i mod_jk
mod_jk/1.2.18 <-- There you go. 2. If you have that already installed then if you have enable mod_jk log then you can check from that log file or you can do http://Your_SERVER/ApplicationURL/SomeFOLDER/@#@#CS<>>$#$#$% You will get internal serever error over there at the bottom you will get the mod_jk version with apache version. e.g. Apache/2.0.59 (Unix) mod_jk/1.2.28