Nearly half of the 1,000 people surveyed by Which? said they do not know what the new rate will be when the new state pension comes into force next week.
The changes come into effect from Wednesday.
Which? found that 68 per cent of the 50 to 64-year-olds they surveyed were aware changes are taking place.
That figure rose to 80 per cent of those aged between 60 and 64.
Yet some 44 per cent said they did not know what the full rate will be.
Just one in five respondents were aware that the state pension age will be 65 for both men and women by the end of 2018.
"While it's promising to see that awareness of the upcoming changes is high, we're only half way there," said Which? executive director Richard Lloyd. "More needs to be done to make sure that people understand what the changes are and what they mean for them."
The research comes after MPs last month warned that too few people understand the changes to the state pension.