What it means
途中で indicates that something happens during an ongoing activity, journey, or process, or at a point before it reaches its end. With a noun, it usually means “during” or “on the way through” that noun. With a verb, the dictionary form commonly describes an action or destination that is in progress or still ahead, while ている途中で emphasizes that the action itself is currently underway. The event after 途中で often interrupts or occurs before the first action is completed.
Usage note
With a noun, use の途中で. The dictionary-form pattern and the ている途中で pattern are both grammatical but have different nuances: 帰る途中で refers to being on the way to return, whereas 仕事をしている途中で refers to being in the middle of working. Do not treat the て-form as generally impossible before 途中で.
How to use it
旅行の途中で、彼は古い寺を見つけました。
During the trip, he found an old temple.
帰る途中で雨が降り始めました。
On the way home, it began to rain.
映画を見ている途中で、電話が鳴りました。
While watching a movie, the phone rang.
旅行の途中で、彼は古い寺を見つけた。
During the trip, he found an old temple.
帰る途中で雨が降り始めた。
On the way home, it began to rain.
映画を見ている途中で、電話が鳴った。
While watching a movie, the phone rang.