Some children might as well put their pocket money in a piggy bank rather than an actual bank owing to poor rates of interest, research suggests.
Children faced the same pressures as their parents and grandparents as savings rates fell, Moneyfacts said.
The financial information service said some accounts paid just 0.1% a year.
Annual interest paid on a typical child savings account, including fixed term and variable accounts, has fallen from 1.61% a year ago to 1.39% now.
Good habits
A government-backed advice service said that the rates were falling but children should still be urged to save.
Andrew Johnson, from the Money Advice Service, said: "While this may make the prospect of saving less attractive, it's important that people understand the importance of building up a savings buffer."
Last month the service said that more than 16 million adults in the UK have savings of less than £100.
He said that children should be included in the process of setting up savings, and parents should shop around for the best deals to suit everyone's needs.
Children's savings accounts had collectively been the subject of more than 100 rate cuts over the course of the year, according to Moneyfacts.
Those accounts, which have a fluid, or variable, interest rate, have seen rates cut after the Bank of England cut its base rate in August. Most variable rate savings accounts for adults have also been hit by this change.
The best paying accounts still pay nearly 3% a year in interest - higher than the rising cost of living. The worst still pay well below the rate of inflation.
"It is hugely disappointing to see children's savings accounts facing the same treatment as adult accounts," said Rachel Springall, of Moneyfacts.
"As the majority of child savers pay variable rates, they are in danger of rate changes at any moment, so it's worthwhile to be diligent in checking the savings pot on a regular basis and not put up with any paltry interest."
Young savers can get a better return by signing up to accounts that tie them in to making a fixed level of regular saving, while their families can also get slightly better rates on Junior Isas.
These Isas - a variation on regular tax-free Individual Savings Accounts - allow parents, grandparents or family friends to invest in cash or stocks and shares for their children's future.
