The protest, dubbed "a million woman march" and promoted on Twitter under #BringBackOurGirls, will not likely to draw a massive crowd.
But organiser Hadiza Bala Usman told AFP that the turn-out was less important than raising awareness about the plight of the hostages whose 14 April abduction at gunpoint from their school in the northeast has outraged Africa's most populous nation.
"We have put the word out on social media and we hope people will come. But even if only 10 people come, it will be 10 people who are committed to ensuring that these girls are not disregarded," she said.
"The government has to understand that we are not going to allow this silence to continue," Usman added.
The mass kidnapping in the Chibok area of northeastern Borno state was one of the most shocking attacks in Boko Haram's five-year extremist uprising, which has killed thousands across the north and centre of the country.
Borno's government said 129 girls were taken and that 52 have since escaped.
Locals, including the principal at the targeted Government Girls Secondary School in Chibok, have rejected those figures, claiming that 230 teenage students were taken and that 187 are still being held hostage.
Not enough action
The leader of Chibok's elders forum, Pogo Bitrus, told AFP that he had received information indicating the girls were trafficked into neighbouring Cameroon and Chad and sold as brides to insurgent commanders for 2 000 naira ($12).
There was however no independent confirmation of this report.
Parents have voiced fury at the military's apparent rescue operation, accusing the security services of ignoring their daughters.
Bitrus said it was "unbelievable" that the military, which claims to be working around-the-clock to find the hostages, had not yet tracked down any of the kidnappers.
Locals have scoured the bushlands of the remote region, pooling money to buy fuel for motorcycles and cars to conduct their own rescue effort.
Usman condemned what she called the official complacency which has followed the abductions.
"If this happened anywhere else in the world, more than 200 girls kidnapped and no information for more than two weeks, the country would be brought to a standstill," she told AFP.
Boko Haram's name translates as "Western education is forbidden", and it has repeatedly attacked schools during an insurgency aimed at creating a strict Islamic state in mainly Muslim northern Nigeria.
The Islamists have set schools on fire, massacred students in their sleep and detonated bombs at university campus churches, but a massive kidnapping specifically targeting girls is unprecedented.
Parents welcome support
The rally is expected to kick off at the Unity Fountain in central Abuja at 15:00 and move towards the National Assembly.
Usman said she had been promised that the House Speaker Aminu Tambuwal and perhaps even President Goodluck Jonathan will speak to the protesters.
"We have booked an appointment," she said. "We expect [both men] will come out and address us."
Jonathan has faced scathing criticism over his handling of the Boko Haram conflict, which has already killed more than 1 500 people this year.
Speaking by phone from Chibok, a father of one of the kidnapped schoolgirls voiced hope that attention to his nightmare from protesters outside the seat of government could make a difference.
"We are poor with no influence whatsoever, which we believe is the reason the government does not care about our girls," said the father, requesting anonymity.
"We believe if Nigerians, the high and the low, raise their voices from different quarters it will make the government sit up and do the right thing to free our girls."