Hartmann flew in from Paris and was welcomed by the HHO president, Ivan Zvonimir Cicak.
Asked by reporters whether she was afraid of the possibility of being arrested on a warrant issued by the ICTY, Harmann said that she was not afraid in Croatia but that she was afraid in general.
Asked what the award the HHO would bestow on her for her life achievement meant to her, Hartmann said that she did not feel free or know how her day would end.
Hartmann said that she would comment on the HHO award a little later.
She said that she had met with no problems upon her arrival in the Croatian capital.
"Your police have checked whether the international warrant has arrived in Zagreb or not. I don't know if it has arrived. Anyway, the international warrant for my arrest is in contravention of the European convention on human rights," she said.
Earlier in the day, the Croatian interior ministry's spokesman, Krunoslav Borovec, told Hina that there was no warrant for Hartmann's arrest in Croatia.
The Hague tribunal issued the warrant in mid-November.
The ICTY found Hartmann guilty of contempt and fined her 7,000 euros. Since she did not pay the fine, it has been converted into a prison term of seven days. The arrest warrant was issued on November 16.
Hartmann, a French journalist, served as spokeswoman for the then Chief Prosecutor Carla del Ponte from 2000 to 2006. In 2009 she was found guilty of contempt of the tribunal because she had disclosed two confidential court decisions from the trial of former Serbian President Slobodan Milosevic. Hartmann said that the judgement against her relied on non-existent legal standards that granted confidentiality status to documents indicating Serbia's involvement in genocide in Bosnia and Herzegovina.
Hartmann notified the ICTY in writing that her supporters had raised the required sum and paid it into a French bank account from which the tribunal could withdraw it, but the ICTY insists that Hartmann personally pay the fine.
Recently Hartmann turned to the UN Rapporteur on Freedom of Opinion and Expression with a 71-page submission complaining about violations of her right to disclose information of public and general interest.
She also informed the OSCE media freedom officials about her case.
The HHO award-giving ceremony will be held in Zagreb on Saturday.