Police reported that the woman was walking her small dog at about 9 a.m. in the 2200 block of 55th Avenue on July 26 when a stranger approached her.
The man hit the victim on the head with an unknown object and knocked her to the ground. He then physically assaulted and attempted to sexually assault her, police said.
The victim kicked and punched the suspect and yelled for help, and the suspect fled the scene, according to police.
He is described as an African-American man between 50 and 60 years old, 5 feet 10 inches tall, with a slender build. He was wearing a black hooded sweatshirt and black sweatpants. He had a strong body odor and an unkempt appearance, police said.
Crime Stoppers of Oakland is offering a reward of up to $5,000 for information leading to an arrest and conviction in the case. Tips can be reported to the Youth and Family Services Division at (510) 238-3641 or the TIP LINE at (510) 637-0298.
Oakland police are advising members of the public to be aware of their surroundings at all times, and not to be distracted by cellphones or electronic devices.
Pedestrians should stay in well-lit and populated areas, and drivers should be especially alert when entering and exiting their vehicles. If something looks suspicious, residents are advised to call police.