One of the 21 July terror suspects kept a list of explosives on a CD Rom seized by the authorities, a court has heard.
Adel Yahya is one of six men who deny terrorism charges
Adel Yahya, 24, of Tottenham, north London, also stored book titles relating to chemical and biological warfare, Woolwich Crown Court was told.
Mr Yahya said he signed a property list confirming he owned the CD Rom only because he feared it would be stolen.
Mr Yahya and five other men all deny conspiracy to murder and to cause explosions likely to endanger life.
The CD Rom was seized when Mr Yahya was arrested in Ethiopia in November 2005 following a request by UK authorities.
He told the court that the item, which contained a large Excel spreadsheet with 97 chapters written in English, belonged to his uncle in Ethiopia.
One chapter listed details of explosives; another chemicals and a third book titles, including Aircraft Safety, Terrorist Target Selection, Biological Warfare, Chemical Warfare Agents and Jihad: The Origin of the Holy War in Islam.
Another chapter, about chemicals and fertiliser, included 29 sources of hydrogen peroxide in concentrations of 27.5% to 50%.
Max Hill, prosecuting, said: "Your role in this conspiracy included using your knowledge to set about obtaining the highest concentration you and your co-defendants could find."
Mr Yahya denied knowing about the list and said: "What you are saying is absolute rubbish."
Mr Yahya admitted he asked about the highest percentage concentration of hydrogen peroxide sold at a cosmetics shop in Finsbury Park, north London, twice in May and June 2005.
He said he did it because that was what co-defendant Yassin Omar wanted him to ask.
Mr Yahya said the chemical was needed for bleaching wood.
But Mr Hill accused him of wanting a higher percentage to make explosives.
"The truth is Mr Yahya, you were the man who was in charge then, weren't you?" said Mr Hill.
Mr Yahya was also accused by the prosecution of altering bank statements to show balances of zero as well as submitting a fake letter in order to get money from a university fund.
Asked if he told a "pack of lies" to receive the cash from the access to learning fund at London Metropolitan University where he was studying, Mr Yahya replied: "Partly yes."
Mr Hill suggested this demonstrated Mr Yahya was "capable of sophisticated financial dishonesty".
But Mr Yahya told the court his university application had "nothing to do with the conspiracy".
He is one of six men accused of taking part in an extremist Muslim plot to carry out a series of suicide bombings on the London's public transport network in 2005.
In the dock are Ramzi Mohammed, 25, of North Kensington, west London; Hussain Osman, 28, of no fixed address; Muktar Said Ibrahim, 29, from Stoke Newington, north London; Mr Omar, 26, from New Southgate, north London; Mr Yahya; and Manfo Kwaku Asiedu, 34, of no fixed address.
The case continues.