Objectives: Income poverty is one of the most common problems of old age. It varies among older adults living in different societies. This study aims to investigate the predictors of income poverty in older adults based on the data from Organization for Economic Cooperation and Development (OECD) countries. Methods: The secondary data analysis method was used in the present study. The income poverty rate and its associated variables were extracted from 36 members of OECD countries and entered into the SPSS software, version 22. For data analysis, descriptive and inferential statistics, including the Pearson correlation coefficient test and multiple linear regression analysis were employed. Results: The results showed that in the studied countries, the mean of income poverty among older adults was higher in women (11.48±16.2), and the elderly aged 75 years or above (12.57±16.1). The income poverty of older adults was significantly correlated with older adults’ share in the gross domestic product (r=-0.376, P=024), targeted pension coverage (r=-0.505, P=0.003), income sources based on public transfers (r=-0.460, P=0.005), income sources from work (r=0.697, P=0.000), mandatory pension contribution rate (r=-0.343, P=0.040), and net pension replacement rate (r=-0.424, P=0.010). The results of regression analysis also revealed that variables of income sources from work and targeted pension coverage explained 66% of the variance in income poverty among older adults. Discussion: It is important to pay attention to the variables of age and gender of older people to overcome economic vulnerability in social policies. It is also necessary to consider the role of the share of public transfers and basic old-age pensions to reduce older adults’ poverty. The lessons to be learned from OECD countries in this research are useful for the social rehabilitation of older adults in Iran.