The union said its members had been offered a 5% pay rise, describing it as a real pay cut due to rising inflation.
Railway unions are holding a series of strikes over wages, jobs and working conditions in early October that will cripple services in the UK.
RMT general secretary Mick Lynch said: “ScotRail knows this offer is not good enough and needs to be mindful of the escalating cost of living crisis.
“Our members refuse to get poorer and will use their industrial strength to let ScotRail know that they will not rest until they get paid what they deserve.”