There are about 19 daily trains from Bangalore to Mysore, six of them are passenger trains, the rest are express trains.

Another 7 weekly / bi-weekly trains too are available to travel from Bangalore to Mysore.

As thumb rule,  expect a Mysore bound train in every 1 hour or so from Bangalore City (Majestic) during daytime and till night ( 4am to 8pm). There are very few trains in the midnight times, except the passenger train called the Night Queen Passenger

There are two train timetables given below for the Bangalore to Mysore train timings. The first table lists all the daily trains and timings. The second table lists the timings of the weekly/bi weekly express trains from Bangalore side to Mysore.

The timings are listed from the Bangalore City Junction railway station. Some of the trains stop at other railway stations in Bangalore also (like the Whitefield, Bangalore Cantonment, Yesvantpur etc) .

Bangalore City (SBC) to Mysore Junction (MYS) Daily Trains time table.

Timetable for the Weekly and bi-weekly express trains to Mysore via Bangalore. Many of these trains has stops in other stations in Bangalore too. This timetable however lists only timings from the Bangalore City Junction (SBC)

The earliest daily train to Mysore from Bangalore is Kaveri Express, arriving from Chennai Central (Railway Station Code: MAS) (leaves Bangalore City Jn by 4 am) followed by the Bangalore-Mysore Passenger (leaves Bangalore City Jn by 5am).

Similarly the last train to leave for Mysore is the Night Queen Passenger. By the way the passenger trains are the cheapest means to travel between Bangalore and Mysore. Even the sleeper ticket fare in Night Queen Passenger is less than a comparable bus fare!

Also you may want to see the Mysore to Bangalore train timings and  Bangalore to Mysore train fare.

Note: The above details (Bangalore Mysore Train Timings) added in April 2015. Pl check with indian railways website  the official train timings. You can do online reservations @ the irctc.co.in website