Frustrated commuters sent train companies more than 280,000 tweets about delays last year.
A study by Commute London also found more than 70,000 tweets were sent about cancellations, and more than 62,000 were about overcrowding.
The figures are from passengers of 14 companies that run services to London.
First Great Western had the most number of tweets about delays with 45,100 being sent while Southern came top with tweets about cancellations.
The research showed that in 2014:
- Total tweets about the 14 companies reached more than 1.77 million
- The company that passengers tweeted about the most was FGW (265,201 tweets), followed by Virgin Trains (257,254) and Greater Anglia (241,038)
- There were 70,969 tweets directed at the 14 companies using cancellation language such as “cancel”, “replacement” and “bus replacement”
- Some 280,960 tweets used delay language including words such as “delay”, “late” and “stuck”
- More than 62,000 tweets were about overcrowding, using words such as “crowd”, “sardine” and “no seat”
- With nearly 19,000 tweets, Great Northern had the lowest number of total tweets and the fewest about overcrowding (842)
Commute London director Daren Wood said: “Social media sites like Twitter provide commuters with an open forum to make complaints, provide feedback and make themselves heard by others.
“Our analysis shows that the train companies need to make much better use of their Twitter feeds if they wish to keep customers happy by listening and learning from criticism.”
But FGW said it was “proud” of the figures.
In a statement, it said: “Far from being indicative of service delays, what this survey shows is how dedicated FGW is to engaging with our passengers, actively seeking their views and providing them with the information we know they want, at the time they want it.
“Social media allows us to respond more quickly and in real time and far from being ashamed by these figures, we encourage customers to get in touch via @FGW or on Facebook.”
A spokesman for rail industry body the Rail Delivery Group said: “Operators have embraced social media so, when things do go wrong, they can give passengers the latest travel information and help answer queries quickly to allow people to better plan their journey.”