[Nati]

Please, need your help with resolving the following issue

I need to react Barium Peroxide with concentrated hydrochloric acid  HCl,in order to obtain Hydrogen Peroxide H2O2 as concentrated as possible (ca. 5%). I work in 250 cc solution volume.
What concentration of HCl shall I use? And how long should last the reaction?
Should the solution be cooled during the reaction, and if yes – at what temperature shall it be kept?

Moreover, when I neutralize with NaOH  the acidic solution after the BaSO4 precipitation (after adding the diluted H2SO4) – what molarity of NaOH shall be used and what shall be the cooling conditions of the neutralization?

[chenbeier]

Don't use HCl, you would obtain chlorine gas!!!!
You have to use sulfuric acid. You get the hydrogen peroxide and bariumsulfate as precipitate.
Concentration about 1 M. The neutralisation you should monitor with a pH Probe,

[Borek]

Won't it be easier and safer to buy a commercial 30% (or 35%) solution and dilute?