Police investigating the disappearance of Andrew Godsen took the electronics as the pair were held on suspicion of kidnap and human trafficking.
Officers said the devices could take “six to 12 months” to analyse.
Andrew, 14, from Doncaster, was last seen on 14 September 2007. His father Kevin said the arrests had intensified the family’s “emotional journey”.
The men, aged 38 and 45, were arrested in London on 8 December with the assistance of officers from the Metropolitan Police. It is believed they are the first arrests in the case.
The older man was also arrested on suspicion of possessing indecent images of children, South Yorkshire Police said.
In a statement, Andrews family said: “We understand that police investigation will take several months to complete, so until that is the case, we do not know what to think and do not wish to speculate on any possible outcome.”
He added: “We have carried the burden of not knowing for many years and recent potential developments represent a more intensified period of this emotional journey for us.”
On the day of his disappearance on 14 September 2007, Andrew skipped school and withdrew just under £200 from his bank account before buying a one-way ticket to London.
He was last seen on CCTV footage arriving at King’s Cross Station and since then police have been unable to corroborate his movements.
Andrew’s motive for travelling to London on the day he was last seen has never been established.