Chatterjee and Shreevats Goswami were batting on 51 and 21 at close of play.
Openers Easwaran (65) and Mondal (58) gave the visitors a solid start, sharing a 128-run stand.
Samad Fallah, Dominic Muthuswami and Chirag Khurana took a wicket each for Maharashtra.
Captain Rohit Motwani's decision to put the opposition in did not pay off as Bengal batsmen frustrated the home team with gritty knocks.
Brief scores: Bengal 239/3 in 90 overs (Abhimanyu Easwaran 65, Sayan Mondal 58, Sudip Chatterjee 51 not out; Samad Fallah 1/39).
